Question Analysis
This question combines geometric knowledge of angle bisectors with algebraic equation - solving.
Key Concept Explanation
An angle bisector is a ray that splits an angle into two congruent angles. So, if bisects , then , and .
Step - by - Step Solution
1. Set up the equation based on the angle - bisector property:
Given and , we can write the equation .
Expand the left - hand side using the distributive property: .
2. Solve the equation for :
Move the terms to one side. Subtract from both sides: