2010 · Q51
The side BC of the triangle ABC is extended to D. If ∠ACD = 120°, ∠ABC = 2/3 ∠CAB, then what is ∠BAC ?
Elementary MathematicsGeometry
- A60°
- B45°
- C30°
- D72°
Explanation
Exterior ∠ACD=120°; ∠CAB+(2/3)∠CAB=120° gives ∠CAB=72°.
The side BC of the triangle ABC is extended to D. If ∠ACD = 120°, ∠ABC = 2/3 ∠CAB, then what is ∠BAC ?
Explanation
Exterior ∠ACD=120°; ∠CAB+(2/3)∠CAB=120° gives ∠CAB=72°.