(1)证明:∵为直径,, ∴.∴. ········································································ 3分 (2)答:,,三点在以为圆心,以为半径的圆上. ·························· 4分 理由:由(1)知:,∴. ∵,,, ∴.∴.································································· 6分 由(1)知:.∴. ∴,,三点在以为圆心,以为半径的圆上. ···································· 7分 |