Cartesion System


   
 
Question (1): If the distance between the points (5, -6) and (x, -1) is 13, find the positive values of x. [3 Mark]

Answer:  The distance between two points is given by image

Given A (5, -6), B (x, -1), AB = 13

image

image

Squaring both the sides,

image

image

image

image

image

Solving this quadratic equation,

image

image

image

image

Given x is a positive value, hence x = 17.
Question (2): Show that the point A (7, 7) is equidistant from the points B (3, 4) and C (4, 3). [3 Mark]

Answer:  Given, A (7, 7) is equidistant from B (3, 4) and C (4, 3)image

Hence AB is given by distance formula, image

image

image

image

image

= 5 units

image

image

image

image

= 5 units

Hence AB = AC
Question (3): Calculate the distance between the points P(3, 5), Q(6, 7). Leave your answer in root form. [2 Mark]

Answer:  image

imageA(x1, y1), B(x2, y2) distance between AB by distance formula is,

image

image

image

image
Question (4): Calculate the distance between the points (-3, 5) and (4, -6), leave your answer in surd form. [2 Mark]

Answer:  Let A(-3, 5) and B(4, -6)

image

image

image

image

image

image
Question (5): Prove that the points A(-5, 4), B(-1, -2) and C(5, 2) are the vertices of an isosceles right angled triangle. [3 Mark]

Answer:  Given that ABC is a triangle.

image

If ABC is an isosceles D le, then AB = BC.

image

image

image

image

image

image

Hence ABC is an isosceles triangle.

If it is a right angled triangle then,

AC2 = AB2 + BC2

image

image

image

AC2 = 104 units

image

image

= 2 x 52

= 104 units

Hence AC2 = AB2 + BC2 and AB = BC

image is an isosceles right angled triangle.
Question (6): Prove that the points (3, 1), (4, 3), (0, 3) and (-1, 1) are the vertices of a parallelogram. Or diagonals bisect each other. [3 Mark]
Hint:
Show that the opposite sides are equal


Answer:  image

Let A(3, 1), B(4, 3), C(0, 3), D(-1, 1) the vertices of a (parallelogram) Quadrilateral.

In a parallelogram opposite sides are equal and parallel.

Hence if AB = CD and AD = BC, then ABCD is a parallelogram.

By distance formula,

image

image

image

image

image

image

image

image

image

Hence one pair of opposite sides are equal.

Consider AD and BC,

image

image

image

= 4 units

image

image

image

image

= 4 units

Hence AB = DC and AD = BC

imageABCD is a parallelogram.
Question (7): Prove that the triangle PQR with vertices P (5, -3), Q (5, 0), R (2, 0) is an isosceles triangle. [2 Mark]

Answer:  image

If triangle PQR is an isosceles triangle then either PQ = QR,

(or any 2 sides are equal)

image

PQ image

image

image

image

image

= 3 units

image

image

image

PQ = QR Hence imageis isosceles.
Question (8): Find the Co-ordinates of the points whose abscissa is 10 and which are at a distance of 10 units from (2, -3). [3 Mark]

Answer:  Let the point A whose abscissa is 10 have the co-ordinates as A (10, y).

Another point B (2, -3)

AB = 10 units (given)

According to distance formula,

image

image

image

image

image

image

Squaring both the sides,

100 = y2 + 6y + 73

image

Solving the quadratic,

imagey2 + 6y - 27 = 0

imagey2 + 9y - 3y - 27 = 0

imagey(y + 9) - 3(y + 9) = 0

image (y + 9(y - 3) = 0

imagey = -9 or y = 3

Vertices of ordinates are -9 or 3

Points are, (10, -9) or (10, 3)
Question (9): Prove that A (-4, 3), B (0, 9), C (-3, 11) and D (-7, 5) form a parallelogram ABCD. [3 Mark]

Answer:  If ABCD are the vertices of the parallelogram, then their opposite sides are equal in length and parallel.

imageAB = CD and BC = AD

image

image

image

image

image

image

image

Hence AB = CD

image

image

image

image

image

image

image

image Hence BC = AD

imageABCD is a parallelogram.
Question (10): Prove that P (-5, 4), Q (-1, -2), R (5, 2) and S (1, 8) form a square PQRS. [3 Mark]

Answer: 

image

According to the property of square, if PQRS is a square then all the sides are equalimagePR = QS

image

image

image

image

image

image

image

image

image

image

image

image

image

image

image

image Hence PQ = QR = RS = SP.

imageAll the sides are equal.

One of the diagonals,

image

image

image

image

image

image

image

image

image

Hence PR = SQ

imageDiagonals are equal.

Hence PQRS is a square.
Question (11): The vertices P(2, -3), Q(5, 1), R(1, 4) and S(-2, 0) form a square. Verify it and show that each side of the square is 5 units. [3 Mark]

Answer:  image

If PQRS is a square, then PQ = QR = RS = SP.

image

image

image

image

image

= 5 units

image

image

image

image

= 5 units

image

image

image

image

image

= 5 units

image

image

image

image

= 5 units

Hence PQRS is a square of 5 units.
Question (12): Find the coordinates of the points on the X-axis which are at a distance of imageunits from the point (8, -3). [3 Mark]

Answer:  Points on the X-axis has y coordinate or ordinate = 0. Let the x coordinate or abscissa be a.

Let A(a, 0) and B(8, -3)

image

image

image

image

image

image

image

Squaring on both sides,

image

image

image

image

image

image

image

image

Hence the coordinates of the points are (14, 0) or (2, 0).
Question (13): Find the coordinate of the point P which is equidistant from A (5, 5), B (-2, 4) and C (- 2, -2). Hence find AP. [3 Mark]

Answer:  Given P(x, y) is equidistant from A(5, 5), B(-2, 4), C(-2, -2)

Then PA = PB = PC

According to distance formula,

image

image

image

Given PA = PB

image

Squaring both the sides,

(5 - x)2 + (5 - y)2 = (-2 - x)2 + (4 - y)2

image

image

image

PB = PC

image

Squaring both the sides,

(-2 - x)2 + (-2 - y)2 = (-2 - x)2 + (4 - y)2

image

image

image

image

image

Substituting the values of y = 1 in 15 - 7x - y = 0

image

image

image

Hence the coordinates of P(2, 1)

image

image

image

image

imagePA = 5 units
Question (14): Abscissa of a point P equals its ordinate. If P is equidistant from A (5, -3) and B (8, - 4), find the coordinates of the point P. [3 Mark]

Answer:  Given, Abscissa = ordinate for a point.

P = (a, a)

image

By distance formula,

image

image

But PA = PB

image

Squaring both the sides,

(a - 5)2 + (a + 3)2 = (a - 8)2 + (a + 4)2

a2 + 25 - 10a + a2 + 6a + 9 = a2 + 64 - 16a + a2 + 16 + 8a

image

image

image

image

imageCoordinates of point P(11.5, 11.5)

Question (15): The ordinate of point P is greater than its abscissa by 3 units. Its distance from a point A (-4, -8) is 17 units. Find the coordinates of the point P if it in the first quadrant. [3 Mark]

Answer:  Let the coordinates of point P (x, y)

given, y = x + 3 and PA = 17, Now P(x, x+3)

By distance formula,

image

Squaring both the sides,

172 = (x + 4)2 + (x + 11)2

289 = (x + 4)2 + (x + 11)2

289 = x2 + 16 + 8x + x2 + 121 + 22x

289 = 2x2 + 30x + 137

0 = 2x2 + 30x + 137 - 289

0 = 2x2 + 30x - 152

image

0 = x2 + 19x - 4x - 76

0 = x(x + 19) - 4(x + 19)

0 = (x + 19)(x - 4)

image

But given abscissa and ordinate lie in 1st quadrant.

imageBoth are +ve values.

Hence x = 4 then y = x + 3 = 4 + 3 = 7

imageCoordinates of P(4, 7).
Question (16): Abscissa of a point P is twice its ordinate. If the point P is equidistant from (+2, -5) and (-3, 6), find its co-ordinates. [3 Mark]

Answer:  Given P(x, y) be the point.

Given, abscissa is twice its ordinate.

image

image

P is equidistant from A (2, -5), B (-3, 6)

image

by distance formula,

image

image

Given PA = PB

image

Squaring both the sides,

image

image

image

image

image

Hence x = 16

imageP (16, 8)
Question (17): If the point (x, y) is equidistant from (-2, 1) and (1, -3), prove that 6x - 8y = 5. [3 Mark]

Answer:  Given P(x, y) is equidistant from A (-2, 1) and B (1, -3)

imagePA = PB

By distance formula,

image

image

Given, PA = PB

image

Squaring both sides,

(x + 2)2 + (y - 1)2 = (x - 1)2 + (y + 3)2

image

image

image

image

image

Hence proved.
Question (18): Calculate the co-ordinates of the point P which divides the line joining A (-3, 3) and B (2, -7) internally in the ratio 2: 3. [2 Mark]

Answer: 

image

The co-ordinates of P are given by

image

image
Question (19): Find the co-ordinates of the points of trisection of the line segment joining the points (3, -3) and (6, 9). [3 Mark]

Answer:  image

AB is divided into 3 equal parts

image

image

imageP is the point on AB, which divides AB in the ratio 1:2.

Let (x1, y1) be the co-ordinates of P which divides A (3, -3) and B (6, 9) in the ratio 1:2.

Then image

image

imageThe co-ordinates P are (4, 1)

image

imageare the co-ordinates of Q, Q divides AB in the ratio 2:1

image

image

imageThe co-ordinates of Q are (5, 5).
Question (20): In what ratio does the point (5, 4) divide the line segment joining the points (2, 1) and (7, 6)? [2 Mark]

Answer:  image

Let P (5, 4) divides the line segment AB in the ratio image:1

image

image

imageThe point P divides AB in the ratio 3:2.
Question (21): Calculate the ratio in which the line segment joining (3, 4) and (-2, 1) is divided by the y-axis. [2 Mark]

Answer:  image

On the y-axis, the abscissa is 0. Let the point (0, y) divide the line joining A (3, 4) and (-2, 1) in the ratio k: 1. Then, using section formula, we haveimage

image

image

imageThe required ratio is k: 1

image
Question (22): In what ratio the line joining the points (4, 2) and (3, -5) is divided by the x-axis? Also, find the co-ordinates of the point of division. [2 Mark]

Answer:  image

On the x-axis, y-co-ordinate is zero.

Let P(x, 0) be the point which divides the line joining (4, 2) and (3, -5) in the ratio k: 1.

Using section formula, we have

image

image

image

The required ratio is k: 1=image

= 2:5

image

image
Question (23): The line joining the points A (-3, -10) and B (-2, 6) is divided by the point P such thatimage. Find the co-ordinates of P [3 Mark]

Answer:  image

image

image

image

image

image

imageP divides the line segment AB in the ratio 4:1.

Let (x, y) be the co-ordinates of P.

image

image

image
Question (24): P is a point on the line joining A (4, 3) and B (-2, -6) such that 5AP = 2BP. Find the co-ordinates of P. [2 Mark]

Answer:  image

image

Let the co-ordinates of P be (x, y).

Using Section Formula, we have

image

image

image
Question (25): In what ratio does the point (a, 6) divide the join of (-4, 3) and (2, 8)? Also, find the value of a. [2 Mark]

Answer:  Let P (a,6) divide the line segment A(-4,3) and B(2,8) in the ratio image:1. Then, taking the y-co-ordinate of P, we have

image

image

image

x-co-ordinate of P is given by

image
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