How do you simplify the expression by using a double-angle formula or a half-angle formula for #cos^2(theta/4)-sin^2(theta/4)#? Trigonometry Trigonometric Identities and Equations Double Angle Identities 1 Answer Nghi N. · Becca M. · Jim H Apr 25, 2015 #cos^2 (x/4) - sin^2 (x/4) = cos 2(x/4) = cos (x/2)# Answer link 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#? See all questions in Double Angle Identities Impact of this question 2968 views around the world You can reuse this answer Creative Commons License
