Question

. In the diagram below, find the values of
i. x
ii. y
​

Answer 1

• x = 20°
• y = 40°

Explanation:

You want the values of x and y in the triangle shown.

i. Linear pair

The angles marked 4x and 5x form a linear pair, so have a total measure of 180°:

4x +5x = 180°

9x = 180° . . . . . . combine terms

x = 20° . . . . . . . . divide by 9

ii. Angle sum

The sum of angles in the triangle is 180°, so we have ...

y + 3x + 4x = 180°

y + 7(20°) = 180° . . . . . . substitute the value of x, collect terms

y = 40° . . . . . . . . . . . subtract 140°

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