11(1)连接AQ、BQ;AB是直径,∴∠AQB=90°;∠QAB=∠QPB=45°【同弧QB上的圆周角相等】;∴AQ=BQAQ²+BQ²=AB²2BQ²=2²BQ=√2;(2)连接AP、AQ;AB是直径,∴∠APB=∠AQB=90°;∠APQ=180°-∠APB-45°=180°-90°-45°=45°∠ABQ=∠APQ=45°【同弧QB上的圆周角相等】;∴AQ=BQAQ²+BQ²=AB²2BQ²=2²BQ=√2;