Question

If cos(x-y)=-1,then cosx+cosy=

Answer 1

Step-by-step explanation:

cosx-y=-1

⇒cosx-y=cosπ

⇒x-y=π

⇒x=π+y

Now,

cosx+cosy

-cosy+cosy

=0

Ans:0

MARK ME AS BRAINLIEST