How do you simplify cos4x−sin4x? Trigonometry Trigonometric Identities and Equations Half-Angle Identities 1 Answer Nghi N May 23, 2018 cos 2x Explanation: f(x)=cos4x−sin4x=(cos2x−sin2x)(cos2x+sin2x) Reminder of trig identities: cos2x−sin2x=cos2x (sin2x+cos2x)=1 Therefor, f(x)=cos2x Answer link Related questions What is the Half-Angle Identities? How do you use the half angle identity to find cos 105? How do you use the half angle identity to find cos 15? How do you use the half angle identity to find sin 105? How do you use the half angle identity to find tan(π8)? How do you use half angle identities to solve equations? How do you solve sin2θ=2sin2θ2 over the interval [0,2π]? How do you find the exact value for sin105 using the half‐angle identity? How do you find the exact value for cos165 using the half‐angle identity? How do you find the exact value of cos15using the half-angle identity? See all questions in Half-Angle Identities Impact of this question 77649 views around the world You can reuse this answer Creative Commons License