1.	A line L passes through A(1, –1, 2) and is parallel to the line r = .
(a)	Write down a vector equation for L in the form r =  a + tb.
(2)
 
	The line L passes through point P when t = 2.
(b)	Find
(i)	;
(ii)	.
(4)
(Total 6 marks)

2.	The following diagram shows the obtuse-angled triangle ABC such that
.
		
diagram not to scale
 
(a)	(i)	Write down .
(ii)	Find .
(3)

(b)	(i)	Find .
(ii)	Hence, find .
(7)
 
	The point D is such that , where p > 0.
(c)	(i)	Given that , show that p = 3.
(ii)	Hence, show that  is perpendicular to .
(6)
(Total 16 marks)

3.	The following diagram shows quadrilateral ABCD, with .
		
diagram not to scale
 
(a)	Find .
(2)
 
(b)	Show that .
(2)

(c)	Show that vectors  are perpendicular.
(3)
(Total 7 marks)

4.	The line L1 is represented by the vector equation r = .
	A second line L2 is parallel to L1 and passes through the point B(–8, –5, 25).
 
(a)	Write down a vector equation for L2 in the form r = a + tb.
(2)
 
	A third line L3 is perpendicular to L1 and is represented by r = .
(b)	Show that k = –2.
(5)
 
	The lines L1 and L3 intersect at the point A.
(c)	Find the coordinates of A.
(6)
 
	The lines L2 and L3 intersect at point C where .
(d)	(i)	Find .
(ii)	Hence, find ||.
(5)
(Total 18 marks)

5.	Let  and .
(a)	Find 
(2)
 
(b)	Find a unit vector in the direction of .
(3)
 
(c)	Show that  is perpendicular to .
(3)
(Total 8 marks)

6.	The diagram shows quadrilateral ABCD with vertices A(1, 0), B(1, 5), C(5, 2) and D(4, –1).
		
diagram not to scale

(a)	(i)	Show that .
(ii)	Find .
(iii)	Show that  is perpendicular to .
(5)
 
	The line (AC) has equation r = u + sv.
(b)	(i)	Write down vector u and vector v.
(ii)	Find a vector equation for the line (BD).
(4)
 
	The lines (AC) and (BD) intersect at the point P(3, k).
(c)	Show that k = 1.
(3)
 
(d)	Hence find the area of triangle ACD.
(5)
(Total 17 marks)

7.	The vertices of the triangle PQR are defined by the position vectors
		.
(a)	Find
(i)	;
(ii)	.
(3)

(b)	Show that .
(7)
 
(c)	(i)	Find .
(ii)	Hence, find the area of triangle PQR, giving your answer in the form .
(6)
(Total 16 marks)

8.	Find the cosine of the angle between the two vectors 3i + 4j + 5k and 4i – 5j – 3k.
(Total 6 marks)

9.	The line L1 is parallel to the z-axis. The point P has position vector  and lies on L1.
(a)	Write down the equation of L1 in the form r = a + tb.
(2)
 
	The line L2 has equation r = . The point A has position vector .
(b)	Show that A lies on L2.
(4)

	Let B be the point of intersection of lines L1 and L2.
(c)	(i)	Show that .
(ii)	Find .
(7)
 
(d)	The point C is at (2, 1, –4). Let D be the point such that ABCD is a parallelogram.
Find .
(3)
(Total 16 marks)

10.	(a)	Let u =  and w = . Given that u is perpendicular to w, find the value of p.
(3)
 
(b)	Let v = . Given that , find the possible values of q.
(3)
(Total 6 marks)

11.	Consider the points P(2, –1, 5) and Q(3, –3, 8). Let L1 be the line through P and Q.
(a)	Show that .
(1)
 
(b)	The line L1 may be represented by r = .
(i)	What information does the vector  give about L1?
 
(ii)	Write down another vector representation for L1 using .
(3)
 
	The point T (–1, 5, p) lies on L1.
(c)	Find the value of p.
(3)
 
	The point T also lies on L2 with equation .
 
(d)	Show that q = –3.
(3)
 
(e)	Let θ be the obtuse angle between L1 and L2. Calculate the size of θ.
(7)
(Total 17 marks)

12.	Consider the points A (1, 5, 4), B (3, 1, 2) and D (3, k, 2), with (AD) perpendicular to (AB).
(a)	Find
(i)	
(ii)	, giving your answer in terms of k.
(3)
(b)	Show that k = 7.
(3)
The point C is such that  = 
(c)	Find the position vector of C.
(4)
(d)	Find .
(3)
(Total 13 marks)

13.	Let v = 3i + 4 j + k and w = i + 2 j – 3k. The vector v + pw is perpendicular to w.
Find the value of p.
(Total 7 marks)

14.	The point O has coordinates (0, 0, 0), point A has coordinates (1, –2, 3) and point B has coordinates (–3, 4, 2).
(a)	(i)	Show that  = 
(ii)	Find .
(8)

(b)	The line L1 has equation 
Write down the coordinates of two points on L1.
(2)
 
(c)	The line L2 passes through A and is parallel to.
(i)	Find a vector equation for L2, giving your answer in the form r = a + tb.
(ii)	Point C (k, –k, 5) is on L2. Find the coordinates of C.
(6)
 
(d)	The line L3 has equation  and passes through the point C.
Find the value of p at C.
(2)
(Total 18 marks)

15.	The line L1 is represented by r1 =  and the line L2 by r2 = 
The lines L1 and L2 intersect at point T. Find the coordinates of T.
(Total 6 marks)

16.	A particle is moving with a constant velocity along line L. Its initial position is A(6, –2, 10). After one second the particle has moved to B(9, –6, 15).
(a)	(i)	Find the velocity vector, .
(ii)	Find the speed of the particle.
(4)
 
(b)	Write down an equation of the line L.
(2)
(Total 6 marks)

 and passes through the point C.
Find the value of p at C.
(2)
(Total 18 marks)

17.	The diagram shows a parallelogram ABCD.
		
diagram not to scale
	The coordinates of A, B and D are A(1, 2, 3), B(6, 4, 4) and D(2, 5, 5).
 
(a)	(i)	Show that .
(ii)	Find .
(iii)	Hence show that .
(5)
 
(b)	Find the coordinates of point C.
(3)
 
(c)	(i)	Find .
(ii)	Hence find angle A.
(7)
 
(d)	Hence, or otherwise, find the area of the parallelogram.
(3)
(Total 18 marks)

18.	Consider the points A(5, 8), B(3, 5) and C(8, 6).
(a)	Find
(i)	;
(ii)	.
(3)
 
(b)	(i)	Find .
(ii)	Find the sine of the angle between  and .
(3)
(Total 6 marks)

19.	Two lines L1 and L2 are given by r1 =  and r2 = .
(a)	Let θ be the acute angle between L1 and L2. Show that cosθ = .
(5)
 
(b)	(i)	P is the point on L1 when s = 1. Find the position vector of P.
(ii)	Show that P is also on L2.
(8)
 
(c)	A third line L3 has direction vector . If L1 and L3 are parallel, find the value of x.
(3)
(Total 16 marks)

20.	Consider the vectors u = 2i + 3 j − k and v = 4i + j − pk.
(a)	Given that u is perpendicular to v find the value of p.
(b)	Given that =14, find the value of q.
(Total 6 marks)

21.	Points P and Q have position vectors −5i +11j −8k and −4i + 9 j − 5k respectively, and both lie on a line L1.
(a)	(i)	Find .
(ii)	Hence show that the equation of L1 can be written as
		r = (−5 + s) i + (11− 2s) j + (−8 + 3s) k.
(4)
 
The point R (2, y1, z1) also lies on L1.
(b)	Find the value of y1 and of z1.
(4)
 
The line L2 has equation r = 2i + 9 j +13k + t (i + 2 j + 3k).
(c)	The lines L1 and L2 intersect at a point T. Find the position vector of T.
(7)

(d)	Calculate the angle between the lines L1 and L2.
(7)
(Total 22 marks)

22.	In this question, distance is in metres, time is in minutes.
Two model airplanes are each flying in a straight line.
	At 13:00 the first model airplane is at the point (3, 2, 7). Its position vector after t minutes is given by =  + t .
(a)	Find the speed of the model airplane.
(2)
 
	At 13:00 the second model airplane is at the point (– 5, 10, 23). After two minutes, it is at the point (3, 16, 39).
(b)	Show that its position vector after t minutes is given by =  + t .
(3)
 
(c)	The airplanes meet at point Q.
(i)	At what time do the airplanes meet?
(ii)	Find the position of Q.
(6)
 
(d)	Find the angle q between the paths of the two airplanes.
(6)
(Total 17 marks)

23.	The diagram below shows a cuboid (rectangular solid) OJKLMNPQ. The vertex O is (0, 0, 0), J is (6, 0, 0), K is (6, 0, 10), M is (0, 7, 0) and Q is (0, 7, 10).

(a)	(i)	Show that  = .
(ii)	Find .
(2)
 
(b)	An equation for the line (MK) is r =  + s.
(i)	Write down an equation for the line (JQ) in the form r = a + tb.
(ii)	Find the acute angle between (JQ) and (MK).
(9)
 
(c)	The lines (JQ) and (MK) intersect at D. Find the position vector of D.
(5)
(Total 16 marks)

24.	The points P(−2, 4), Q (3, 1) and R (1, 6) are shown in the diagram below.

(a)	Find the vector .
(b)	Find a vector equation for the line through R parallel to the line (PQ).
(Total 6 marks)

25.	The position vector of point A is 2i + 3 j + k and the position vector of point B is 4i − 5 j + 21k.
(a)	(i)	Show that  = 2i −8 j + 20k.
(ii)	Find the unit vector u in the direction of .
(iii)	Show that u is perpendicular to .
(6)
Let S be the midpoint of [AB]. The line L1 passes through S and is parallel to .
 
(b)	(i)	Find the position vector of S.
(ii)	Write down the equation of L1.
(4)
The line L2 has equation r = (5i +10 j +10k) + s (−2i + 5 j − 3k).
 
(c)	Explain why L1 and L2 are not parallel.
(2)

(d)	The lines L1 and L2 intersect at the point P. Find the position vector of P.
(7)
(Total 19 marks)

26.	The following diagram shows a solid figure ABCDEFGH. Each of the six faces is a parallelogram.

The coordinates of A and B are A (7, –3, –5), B(17, 2, 5).
(a)	Find
(i)	
(ii)	
(4)
 
The following information is given.
	 = ,  = 9,  = ,  = 6

(b)	(i)	Calculate •.
(ii)	Calculate •.
(iii)	Calculate •.
(iv)	Hence, write down the size of the angle between any two intersecting edges.
(5)
 
(c)	Calculate the volume of the solid ABCDEFGH.
(2)
 
(d)	The coordinates of G are (9, 14, 12). Find the coordinates of H.
(3)
 
(e)	The lines (AG) and (HB) intersect at the point P.
Given that  =, find the acute angle at P.
(5)
(Total 19 marks)

27.	The line L passes through the points A (3, 2, 1) and B (1, 5, 3).
(a)	Find the vector .
 
(b)	Write down a vector equation of the line L in the form r = a + tb.
(Total 6 marks)

28.	The line L passes through A (0, 3) and B (1, 0). The origin is at O. The point R (x, 3 − 3x) is on L, and (OR) is perpendicular to L.
(a)	Write down the vectors  and .
(b)	Use the scalar product to find the coordinates of R.
(Total 6 marks)

29.	The diagram shows a cube, OABCDEFG where the length of each edge is 5cm. Express the following vectors in terms of i, j and k.

(a)	;
(b)	;
(c)	.
(Total 6 marks)

30.	Find the cosine of the angle between the two vectors  and .
Working:		
	Answer:
....……………………………………..........	
(Total 6 marks)

31.	In this question the vector  represents a displacement of 1 km east,
and the vector  represents a displacement of 1 km north.
	The diagram below shows the positions of towns A, B and C in relation to an airport O, which is at the point (0, 0). An aircraft flies over the three towns at a constant speed of 250 km h–1.

	Town A is 600 km west and 200 km south of the airport. 
Town B is 200 km east and 400 km north of the airport. 
Town C is 1200 km east and 350 km south of the airport.

(a)	(i)	Find .
(ii)	Show that the vector of length one unit in the direction of  is .
(4)
 
	An aircraft flies over town A at 12:00, heading towards town B at 250 km h–1.
	Let  be the velocity vector of the aircraft. Let t be the number of hours in flight after 12:00. The position of the aircraft can be given by the vector equation
.
 
(b)	(i)	Show that the velocity vector is .
(ii)	Find the position of the aircraft at 13:00.
(iii)	At what time is the aircraft flying over town B?
(6)
 
	Over town B the aircraft changes direction so it now flies towards town C. It takes five hours to travel the 1250 km between B and C. Over town A the pilot noted that she had 17 000 litres of fuel left. The aircraft uses 1800 litres of fuel per hour when travelling at 250 km h–1. When the fuel gets below 1000 litres a warning light comes on.
(c)	How far from town C will the aircraft be when the warning light comes on?
(7)
(Total 17 marks)

32.	A boat B moves with constant velocity along a straight line. Its velocity vector is given by
v = .
At time t = 0 it is at the point (−2, 1).
(a)	Find the magnitude of v.
(b)	Find the coordinates of B when t = 2.
(c)	Write down a vector equation representing the position of B, giving your answer in the form r = a + tb.

(Total 6 marks)

33.	Consider the point D with coordinates (4, 5), and the point E, with coordinates (12, 11).
(a)	Find .
(2)
 
(b)	Find .
(2)

(c)	The point D is the centre of a circle and E is on the circumference as shown in the following diagram.

	The point G is also on the circumference. is perpendicular to . Find the possible coordinates of G.
(8)
(Total 12 marks)

34.	Car 1 moves in a straight line, starting at point A (0, 12). Its position p seconds after it starts is given by  = + p.
(a)	Find the position vector of the car after 2 seconds.
(2)
	Car 2 moves in a straight line starting at point B (14, 0). Its position q seconds after it starts is given by  = + q.
Cars 1 and 2 collide at point P.
(b)	(i)	Find the value of p and the value of q when the collision occurs.
(ii)	Find the coordinates of P.
(6)
(Total 8 marks)

35.	Two lines L1 and L2 have these vector equations.
	L1 : r = 2i + 3j + t(i– 3j)
L2 : r = i + 2j + s(i – j)
	The angle between L1 and L2 is q. Find the cosine of the angle q.
Working:		
	Answer:
…………………………………………..	
(Total 6 marks)

36.	The points A and B have the position vectors  and  respectively.
(a)	(i)	Find the vector .
(ii)	Find .
(4)
	The point D has position vector 
(b)	Find the vector  in terms of d.
(2)
	The angle  is 90°.
(c)	(i)	Show that d = 7.
(ii)	Write down the position vector of the point D.
(3)
	The quadrilateral ABCD is a rectangle.
(d)	Find the position vector of the point C.
(4)
(e)	Find the area of the rectangle ABCD.
(2)
(Total 15 marks)

37.	Points A, B, and C have position vectors 4i + 2j, i – 3j and – 5i – 5j. Let D be a point on the x-axis such that ABCD forms a parallelogram.
(a)	(i)	Find .
(ii)	Find the position vector of D.
(4)
 
(b)	Find the angle between  and .
(6)

	The line L1 passes through A and is parallel to i + 4j. The line L2 passes through B and is parallel to 2i + 7j. A vector equation of L1 is r = (4i + 2j) + s(i + 4j).
(c)	Write down a vector equation of L2 in the form r = b + tq.
(1)
 
(d)	The lines L1 and L2 intersect at the point P. Find the position vector of P.
(4)
(Total 15 marks)

38.	The vector equations of two lines are given below.
	r1 =  + l,   r2 =  + t
	The lines intersect at the point P. Find the position vector of P.
Working:		
	Answer:
..................................................................	
(Total 6 marks)

39.	Consider the vectors c = 3i + 4j and d = 5i – 12j.
	Calculate the scalar product c×d.
Working:		
	Answer:
..................................................................	
(Total 2 marks)

40.	The diagram shows a parallelogram OPQR in which  = ,  = 

(a)	Find the vector .
(3)
 
(b)	Use the scalar product of two vectors to show that cos = – 
(4)

(c)	(i)	Explain why cos = –cos
(ii)	Hence show that sin = .
(iii)	Calculate the area of the parallelogram OPQR, giving your answer as an integer.
(7)
(Total 14 marks)

41.	A vector equation for the line L is r = + t .
	Which of the following are also vector equations for the same line L?
A.	r = + t .
B.	r = + t .
C.	r = + t .
D.	r = + t .
Working:		
	Answer:
……..................................................................
……..................................................................	
(Total 6 marks)

42.	(a)	Find the scalar product of the vectors  and .
(b)	Two markers are at the points P (60, 25) and Q (–30, 40). A surveyor stands at O (0, 0) and looks at marker P. Find the angle she turns through to look at marker Q.
Working:		
	Answers:
(a)	..................................................................
(b)	..................................................................	
(Total 6 marks)

43.	The diagram shows points A, B and C which are three vertices of a parallelogram ABCD. The point A has position vector 

(a)	Write down the position vector of B and of C.
(2)
 
(b)	The position vector of point D is . Find d.
(3)
 
(c)	Find .
(1)
 
	The line L passes through B and D.
(d)	(i)	Write down a vector equation of L in the form
	= + t
(ii)	Find the value of t at point B.
(3)

(e)	Let P be the point (7, 5). By finding the value of t at P, show that P lies on the line L.
(3)
 
(f)	Show that  is perpendicular to .
(4)
(Total 16 marks)

44.	A vector equation of a line is , t Î .
	Find the equation of this line in the form ax + by = c, where a, b, and c Î .
Working:		
	Answer:
......................................................................	
(Total 6 marks)

45.	Calculate the acute angle between the lines with equations
	r =  + s and    r =  + t
Working:		
	Answer:
......................................................................	
(Total 6 marks)

46.	Find the angle between the following vectors a and b, giving your answer to the nearest degree.
a = –4i – 2j
b = i – 7j
Working:		
	Answer:
.......................................................................	
(Total 4 marks)

47.	The diagram below shows a line passing through the points (1, 3) and (6, 5).

	Find a vector equation for the line, giving your answer in the form
, where t is any real number.
Working:		
	Answer:
.......................................................................	
(Total 4 marks)

48.	The diagram below shows the positions of towns O, A, B and X.
Diagram not to scale

	Town A is 240 km East and 70 km North of O.
Town B is 480 km East and 250 km North of O.
Town X is 339 km East and 238 km North of O.
	An airplane flies at a constant speed of 300 km h –1 from O towards A.
 
(a)	(i)	Show that a unit vector in the direction of  is 
(ii)	Write down the velocity vector for the airplane in the form 
(iii)	How long does it take for the airplane to reach A?
(5)
 
	At A the airplane changes direction so it now flies towards B. The angle between the original direction and the new direction is θ as shown in the following diagram. This diagram also shows the point Y, between A and B, where the airplane comes closest to X.
Diagram not to scale

(b)	Use the scalar product of two vectors to find the value of θ in degrees.
(4)
(c)	(i)	Write down the vector .
(ii)	Show that the vector n =  is perpendicular to .
(iii)	By finding the projection of  in the direction of n, calculate the distance XY.
(6)
 
(d)	How far is the airplane from A when it reaches Y ?
(3)
(Total 18 marks)

49.	Find the size of the angle between the two vectors  and . Give your answer to the nearest degree.
Working:		
	Answer:
....................................................................	
(Total 4 marks)

50.	A line passes through the point (4,–1) and its direction is perpendicular to the vector . Find the equation of the line in the form ax + by = p, where a, b and p are integers to be determined.
Working:		
	Answer:
....................................................................	
(Total 4 marks)

51.	In this question the vector  km represents a displacement due east, and the vector  km represents a displacement due north.
	The diagram shows the path of the oil-tanker Aristides relative to the port of Orto, which is situated at the point (0, 0).

	The position of the Aristides is given by the vector equation

	at a time t hours after 12:00.
(a)	Find the position of the Aristides at 13:00.
(2)
 
(b)	Find
(i)	the velocity vector;
(ii)	the speed of the Aristides.
(4)
 
(c)	Find a cartesian equation for the path of the Aristides in the form
ax + by = g .
(4)
 
	Another ship, the cargo-vessel Boadicea, is stationary, with position vector  km.
 
(d)	Show that the two ships will collide, and find the time of collision.
(4)
 
To avoid collision, the Boadicea starts to move at 13:00 with velocity vector km h–1.
(e)	Show that the position of the Boadicea for t ³ 1 is given by

(2)

(f)	Find how far apart the two ships are at 15:00.
(4)
(Total 20 marks)

52.	The vectors u, v are given by u = 3i + 5j, v = i – 2j.
	Find scalars a, b such that a(u + v) = 8i + (b – 2)j.
Working:		
	Answer:
......................................................................	
(Total 4 marks)

53.	Find a vector equation of the line passing through (–1, 4) and (3, –1). Give your answer in the form r = p + td, where t Î .
Working:		
	Answer:
......................................................................	
(Total 4 marks)

54.	In this question, the vector  km represents a displacement due east, and the vector  km a displacement due north.
	Two crews of workers are laying an underground cable in a north–south direction across a desert. At 06:00 each crew sets out from their base camp which is situated at the origin (0, 0). One crew is in a Toyundai vehicle and the other in a Chryssault vehicle.
	The Toyundai has velocity vector  km h–1, and the Chryssault has velocity vector km h–1.

(a)	Find the speed of each vehicle.
(2)
(b)	(i)	Find the position vectors of each vehicle at 06:30.
(2)
(ii)	Hence, or otherwise, find the distance between the vehicles at 06:30.
(3)

(c)	At this time (06:30) the Chryssault stops and its crew begin their day’s work, laying cable in a northerly direction. The Toyundai continues travelling in the same direction at the same speed until it is exactly north of the Chryssault. The Toyundai crew then begin their day’s work, laying cable in a southerly direction. At what time does the Toyundai crew begin laying cable?
(4)

(d)	Each crew lays an average of 800 m of cable in an hour. If they work non-stop until their lunch break at 11:30, what is the distance between them at this time?
(4)
(e)	How long would the Toyundai take to return to base camp from its lunch-time position, assuming it travelled in a straight line and with the same average speed as on the morning journey? (Give your answer to the nearest minute.)
(5)
(Total 20 marks)

55.	The line L passes through the origin and is parallel to the vector 2i + 3j. 
Write down a vector equation for L.
Working:		
	Answer:
......................................................................	
(Total 4 marks)

56.	The triangle ABC is defined by the following information
 = ,            = ,   = 0,            is parallel to .
(a)	On the grid below, draw an accurate diagram of triangle ABC.

(b)	Write down the vector .
Working:		
	Answer:
(b)	..................................................................	
(Total 4 marks)

57.	In this question the vector  km represents a displacement due east, and the vector  km represents a displacement due north.
	The point (0, 0) is the position of Shipple Airport. The position vector r1 of an aircraft Air One is given by
r1 = ,
 
	where t is the time in minutes since 12:00.
(a)	Show that the Air One aircraft
(i)	is 20 km from Shipple Airport at 12:00; 
(ii)	has a speed of 13 km/min.
(4)

(b)	Show that a cartesian equation of the path of Air One is:
5x + 12y = 224.
(3)
	The position vector r2 of an aircraft Air Two is given by
r2 = ,
	where t is the time in minutes since 12:00.
 
(c)	Find the angle between the paths of the two aircraft.
(4)
 
(d)	(i)	Find a cartesian equation for the path of Air Two.
(ii)	Hence find the coordinates of the point where the two paths cross.
(5)
 
(e)	Given that the two aircraft are flying at the same height, show that they do not collide.
(4)
(Total 20 marks)

58.	ABCD is a rectangle and O is the midpoint of [AB].

	Express each of the following vectors in terms of  and 
(a)	
(b)	
 
(c)	
Working:		
	Answers:
(a)	..................................................................
(b)	..................................................................
(c)	..................................................................	
(Total 4 marks)

59.	The vectors , are unit vectors along the x-axis and y-axis respectively.
The vectors  = – + and  = 3 + 5 are given.
(a)	Find  + 2 in terms of  and .
	A vector  has the same direction as  + 2, and has a magnitude of 26.
(b)	Find  in terms of  and .
Working:		
	Answers:
(a)	..................................................................
(b)	..................................................................	
(Total 4 marks)

60.	The circle shown has centre O and radius 6.  is the vector ,  is the vector  and  is the vector .

(a)	Verify that A, B and C lie on the circle.
(3)
(b)	Find the vector .
(2)
 
(c)	Using an appropriate scalar product, or otherwise, find the cosine of angle .
(3)
(d)	Find the area of triangle ABC, giving your answer in the form a, where a Î .
(4)
(Total 12 marks)

61.	The quadrilateral OABC has vertices with coordinates O(0, 0), A(5, 1), B(10, 5) and C(2, 7).
(a)	Find the vectors  and .
(b)	Find the angle between the diagonals of the quadrilateral OABC.
Working:		
	Answers:
(a)	..................................................................
(b)	..................................................................	
(Total 4 marks)