5. ∠AOB = 3∠AOC. ∠AOB, ∠AOC - ?

∠AOB + ∠AOC = 60°

3∠AOC + ∠AOC = 60°

4∠AOC = 60°

∠AOC = 60° / 4 = 15°

∠AOB = 3 × 15° = 45°

Ответ: ∠AOB = 45°, ∠AOC = 15°