How do you simplify #f(theta)=2tan2theta-cos2theta+sec2theta# to trigonometric functions of a unit #theta#? Trigonometry Trigonometric Identities and Equations Double Angle Identities 1 Answer Shwetank Mauria May 3, 2016 #2tan2theta-cos2theta+sec2theta={1+4sinthetacostheta}/(2cos^2theta-1)-(2cos^2theta-1)# Explanation: #f(theta)=2tan2theta-cos2theta+sec2theta# = #2(sin2theta)/(cos2theta)-(2cos^2theta-1)+1/(cos2theta)# = #{1+2(2sinthetacostheta)}/(2cos^2theta-1)-(2cos^2theta-1)# = #{1+4sinthetacostheta}/(2cos^2theta-1)-(2cos^2theta-1)# 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 1423 views around the world You can reuse this answer Creative Commons License