Question

Find the value of x:

Answer 1

x = 20

Explanation:

The sum of the 3 angles in a triangle = 180°

Using ΔAHC , then

∠ACH = 180 - (2x + 100) = 180 - 2x - 100 = 80 - 2x

∠ECD = ∠ACB ( vertical angles are congruent ), thus

∠ECD = ∠ACH + ∠HCB, that is

3x = 80 - 2x + x

3x = 80 - x ( add x to both sides )

4x = 80 ( divide both sides by 4 )

x = 20