2025 · Q18
The measure of and angle formed by the bisectors of the angles A and C of the triangle ABC is 130°. What is the measure of the angle B?
Elementary MathematicsGeometry: Lines, Angles and Triangles
- A65°
- B75°
- C80°
- D85°
Explanation
In the triangle formed by the two internal bisectors and side AC, the angle at the incentre is 130° = 90° + B/2. Thus B/2 = 40°, giving B = 80°, option (c).