Question

Use the squared identities to simplify
2cos^2x cos^2x

a- 3-4cos(2x)-cos(4x)/4
b- 3+4cos(2x)-cos(4x)/4
c- 3+4cos(2x)+cos(4x)/4
d- 3-4cos(2x)+cos(4x)/4

Answer 1

=2cos^4x
=\[2(\cos ^{2}x)^{2}=2[(1+\cos2x)/2]^{2}\]

Answer 2

\[1/2(1+2\cos2x+\cos ^{2}2x)=1/2(1+2\cos2x+(1+\cos4x)/2)\]

Answer 3

\[=1/4(2+4\cos2x+1+\cos4x)=1/4(3+4\cos2x+\cos4x)\]

Answer 4

Thanks