How do you simplify #f(theta)=sin4theta-cos2theta# to trigonometric functions of a unit #theta#? Trigonometry Trigonometric Identities and Equations Double Angle Identities 1 Answer Gerardina C. Jul 4, 2016 #4sinthetacos^3theta-cos^2theta-4sin^3thetacostheta+sin^2theta# Explanation: #f(theta)=2sin(2theta)cos(2theta)-cos(2theta)# #f(theta)=cos(2theta)(2sin(2theta)-1)# #f(theta)=(cos^2theta-sin^2theta)(2*2sinthetacostheta-1)# #f(theta)=(cos^2theta-sin^2theta)(4sinthetacostheta-1)# #4sinthetacos^3theta-cos^2theta-4sin^3thetacostheta+sin^2theta# 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 1522 views around the world You can reuse this answer Creative Commons License