设AC交PB于E
∵BP平分∠ABC，∴∠ABE=20°
∵∠A=60°
∴∠AEB=100°，∴∠PEC=100°
又∵CP平分∠ACD
∴∠ACP=50°
∴∠P=180°-∠PEC-∠ACP=180°-100°-50°=30°
