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Mathematics

Use graph paper for this question :

(i) Draw the graphs of 3x - y - 2 = 0 and 2x + y - 8 = 0. Take 1 cm = 1 unit on both axes and plot three points per line.

(ii) Write down the coordinates of the point of intersection and the area of the triangle formed by the lines and the x-axis.

Coordinate Geometry

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Answer

(i) Given,

⇒ 3x - y - 2 = 0

⇒ y = 3x - 2 …………(1)

When x = 0, y = 3 × 0 - 2 = 0 - 2 = -2,

x = 1, y = 3 × 1 - 2 = 3 - 2 = 1,

x = 2, y = 3 × 2 - 2 = 6 - 2 = 4.

Table of values for equation (1)

x012
y-214

Steps of construction :

  1. Plot the points (0, -2), (1, 1) and (2, 4).

  2. Join the points.

Given,

⇒ 2x + y - 8 = 0

⇒ y = 8 - 2x ………..(2)

When x = 2, y = 8 - 2 × 2 = 8 - 4 = 4,

x = 3, y = 8 - 2 × 3 = 8 - 6 = 2,

x = 4, y = 8 - 2 × 4 = 8 - 8 = 0.

Table of values for equation (2)

x234
y420

Steps of construction :

  1. Plot the points (2, 4), (3, 2) and (4, 0).

  2. Join the points.

Use graph paper for this question : (i) Draw the graphs of 3x - y - 2 = 0 and 2x + y - 8 = 0. Take 1 cm = 1 unit on both axes and plot three points per line. (ii) Write down the coordinates of the point of intersection and the area of the triangle formed by the lines and the x-axis. Coordinate Geometry, ML Aggarwal Understanding Mathematics Solutions ICSE Class 9.

(ii) From the graph,

P(2, 4) is the point of intersection of lines.

BC = 3233\dfrac{2}{3} cm

PV = 4 cm.

Area of triangle = 12\dfrac{1}{2} × base × height

= 12\dfrac{1}{2} × BC × PV

= 12×323\dfrac{1}{2} \times 3\dfrac{2}{3} × 4

= 6236\dfrac{2}{3} cm2.

Hence, P(2, 4) is the point of intersection of lines and area = 6236\dfrac{2}{3} cm2.

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