Question

Solve
cos306+cos234+cos162+cos18​

Answer 1

cos(360-54)+cos(270-36)+cos(180-18)+cos18

=cos54-sin36-cos18+cos18

sin36-sin36

=0

Answer 2

Here is ur answer buddy....

But you must know that,

NOTE:-

cos (180 - theta) = sin theta

cos (180 - theta) = - cos theta