Prove this idenity?
cos6x=2cos(squared)3x -1

cos(6x)=cos(2(3x))=cos(3x)+cos(3x)
applying the sum of angles formula for cosine you get

cos(3x)cos(3x)−sin(3x)sin(3x)=cos^2(3x)−sin^2(3x)

now by the Pythagorean identity for sine and cosine you getcos^2(3x)−(1−cos^2(3x)) finally gathering like terms you get 2cos^2(3x)−1

Your answer would be ahere is how: perimeter is how long all the sides are. in a rectangle, there are two sets of parallel sides. so, to find this, we would to the following.(15x2)+(4x2)30+838if you have questions ask! and mark me brainliest! i really wanna level up : 3