What is the integral of #cos^2(2x)dx#? Calculus Introduction to Integration Integrals of Trigonometric Functions 1 Answer Andrea S. Jan 15, 2017 #int cos^2(2x)dx = x/2 + 1/8sin(4x) + C# Explanation: Use the identity: #cos^2theta= (1+cos2theta)/2# so that: #int cos^2(2x)dx = int (1+cos(4x))/2dx = 1/2intdx + 1/8 int cos(4x)d(4x)= x/2 + 1/8sin(4x) + C# Answer link Related questions How do I evaluate the indefinite integral #intsin^3(x)*cos^2(x)dx# ? How do I evaluate the indefinite integral #intsin^6(x)*cos^3(x)dx# ? How do I evaluate the indefinite integral #intcos^5(x)dx# ? How do I evaluate the indefinite integral #intsin^2(2t)dt# ? How do I evaluate the indefinite integral #int(1+cos(x))^2dx# ? How do I evaluate the indefinite integral #intsec^2(x)*tan(x)dx# ? How do I evaluate the indefinite integral #intcot^5(x)*sin^4(x)dx# ? How do I evaluate the indefinite integral #inttan^2(x)dx# ? How do I evaluate the indefinite integral #int(tan^2(x)+tan^4(x))^2dx# ? How do I evaluate the indefinite integral #intx*sin(x)*tan(x)dx# ? See all questions in Integrals of Trigonometric Functions Impact of this question 106428 views around the world You can reuse this answer Creative Commons License