已知角ACB=90度,若A(7,m),B(3,4)C(1,-2),则M=

问题描述:

已知角ACB=90度,若A(7,m),B(3,4)C(1,-2),则M=

AC=(-6,-2-M),CB=(2,6)
AC*CB=0
-12-12-6M=0
M=-4.