COS 36 DIGREES=?PLEACE TELL THE ANSWER BROTHERS VERY SPEED.

Dear Student,

Assume, x = 18, so 2*x = 36 and 3*x = 54.
Since 2x = 90 – 3x
or sin (2x) = sin(90-3x) = cos 3x
or 2sinx*cosx = 4cos³x – 3cosx,
From here find the value of either cosx or sinx,
Then cos36 = cos 2x = 1 – 2sin²x.

Follow the above steps.

Thanks.