Question

Find the value of x.

Answer 1

A straight line is 180°, so you can do:

109 + ? = 180 (? is the top angle of the triangle)

? = 71°

Because the triangle is an isosceles triangle, the other angle is 71° too.

71 + 71 + ? = 180

? = 38

You subtract 38 with 90 to find the other angle.

90 - 38 = 52°

To find ∠2 you subtract 52 with 180.

180 - 52 = 128

∠2 = 128

128 = 11x + 18

110 = 11x

10 = x