一道几何解答题如图,以正方形ABCD边BC为直径,在正方形内作半圆O,过A作半圆的切线AF,切点为E,AF交BC的延长线

3个回答

  • 连接OE

    △ABC∽△OEF

    OE/OF=AB/AF

    AB=2OE

    AF=2OF

    AB²+BF²=AF²

    AB²+(FO+AB/2)²=4FO²

    5AB²+4AB*FO-12FO²=0

    (-6FO+5AB)(2FO+AB)=0

    FO=5/6AB

    sin∠F=OE/FO=(AB/2)/(5/6AB)=3/5