How to use double angle formula to write #8cos^2x-4#?

Related questions

• What are Double Angle Identities?
• How do you use a double angle identity to find the exact value of each expression?
• How do you use a double-angle identity to find the exact value of sin 120°?
• How do you use double angle identities to solve equations?
• How do you find all solutions for #sin 2x = cos x# for the interval #[0,2pi]#?
• How do you find all solutions for #4sinthetacostheta=sqrt(3)# for the interval #[0,2pi]#?
• How do you simplify #cosx(2sinx + cosx)-sin^2x#?
• If #tan x = 0.3#, then how do you find tan 2x?
• If #sin x= 5/3#, what is the sin 2x equal to?
• How do you prove #cos2A = 2cos^2 A - 1#?