Question

The following figures are not drawn to scale but AB and CD (if present) are straight lines. Find x:

Answer 1

x = 60°

Explanation:

From the figure and the fact that AB and CD are straight lines we can see that:

30° + 2x + ∠DOB = 180° (eq. 1)

x + ∠DOB = 90° (eq. 2)

Subtracting equation 2 to equation 1 we get:

30° + 2x + ∠DOB - (x + ∠DOB) = 180° - 90°

30° + x = 90°

x = 90° - 30°

x = 60°