直线与半圆相切.······················· 1分
证明:法一: 连接,作于点. ∵,∴.·········· 2分 ∵.········· 3分 ∴, ∴.······························· 6分 ∵,∴.····················· 7分 ∴,··························· 8分 ∴, ∴ ∴直线与半圆相切.························· 10分 法二:连接,作于点,作于点. ∵,∴. 在中,·············· 3分 ∵,, ∴四边形是矩形, ∴. ∵,,········ 5分 在中,. ∵, ∴···························· 8分 ∴. ∴直线与半圆相切. |