在平面直角坐标系中:设圆O在原点O(0,0),半径为1,
A(-1,0),B(1,0),C(x,y),且x²+y²=1.
AC=(-1-x,0-y)
BC=(1-x,0-y)
AC·●BC=(-1-x)(1-x)+(0-y)(0-y)
=x²-1+y²
=0.
∴AC⊥BC.证毕.
在平面直角坐标系中:设圆O在原点O(0,0),半径为1,
A(-1,0),B(1,0),C(x,y),且x²+y²=1.
AC=(-1-x,0-y)
BC=(1-x,0-y)
AC·●BC=(-1-x)(1-x)+(0-y)(0-y)
=x²-1+y²
=0.
∴AC⊥BC.证毕.