Question

3.
In the diagram below, AB ABC.
B
(78
А
What is the value of x

Answer 1

x = 129°

Explanation:

Since AB ~ BC then Δ ABC is isosceles and the 2 base angles are congruent.

∠ ACB =
`(180-78)/(2)` =
`(102)/(2)` = 51°

∠ ACB and x are adjacent angles and are supplementary, sum to 180°, then

x = 180 °- 51° = 129°