1.(1+sinx+cosy)/(1+sinx-cosy)=1/2,则cosy=2.若sinA*cosA=60/169(π/4

Question

1.(1+sin x+cos y)/(1+sin x -cos y)=1/2,则cosy=
2.若sin A*cosA=60/169 (π/4

Answer 1

1.cosy=-3/5
2.sin A*cosA=（sin A*cosA）/（sin A^2+cosA^2）=tanA/(tanA^2+1)=60/169
自己解出来即可