已知sin a cos a =1/3求(sin a-cos a)^2的值

问题描述:

已知sin a cos a =1/3求(sin a-cos a)^2的值

(sin a-cos a)^2
=sina^2 - 2sinacosa +cosa^2
= 1- 2sina cosa
= 1-2/3
= 1/3