2018 · Q85
In a triangle ABC, the sides AB, AC are produced and the bisectors of exterior angles of ∠ABC and ∠ACB intersect at D. If ∠BAC = 50°, then ∠BDC is equal to
Elementary MathematicsGeometry: Lines, Angles and Triangles
- A115 °
- B65°
- C55°
- D40°
Explanation
The intersection D of the exterior angle bisectors satisfies angle BDC = 90 degrees - A/2. With A = 50 degrees, angle BDC = 90 - 25 = 65 degrees. Hence option B.