How do you find the integral of int [cos^3 (2x)] dx ∫[cos3(2x)]dx? Calculus Introduction to Integration Integrals of Trigonometric Functions 1 Answer Sasha P. Sep 21, 2015 1/2sin 2x-1/6sin^3 2x+C12sin2x−16sin32x+C Explanation: I=int cos^3 2xdx = int cos 2x cos^2 2x dxI=∫cos32xdx=∫cos2xcos22xdx I=int cos 2x (1-sin^2 2x)dxI=∫cos2x(1−sin22x)dx sin 2x=t => 2cos 2xdx = dt => cos 2xdx = dt/2sin2x=t⇒2cos2xdx=dt⇒cos2xdx=dt2 I=int(1-t^2)dt/2=1/2(t-t^3/3)+CI=∫(1−t2)dt2=12(t−t33)+C I=1/2sin 2x-1/6sin^3 2x+CI=12sin2x−16sin32x+C Answer link Related questions How do I evaluate the indefinite integral intsin^3(x)*cos^2(x)dx∫sin3(x)⋅cos2(x)dx ? How do I evaluate the indefinite integral intsin^6(x)*cos^3(x)dx∫sin6(x)⋅cos3(x)dx ? How do I evaluate the indefinite integral intcos^5(x)dx∫cos5(x)dx ? How do I evaluate the indefinite integral intsin^2(2t)dt∫sin2(2t)dt ? How do I evaluate the indefinite integral int(1+cos(x))^2dx∫(1+cos(x))2dx ? How do I evaluate the indefinite integral intsec^2(x)*tan(x)dx∫sec2(x)⋅tan(x)dx ? How do I evaluate the indefinite integral intcot^5(x)*sin^4(x)dx∫cot5(x)⋅sin4(x)dx ? How do I evaluate the indefinite integral inttan^2(x)dx∫tan2(x)dx ? How do I evaluate the indefinite integral int(tan^2(x)+tan^4(x))^2dx∫(tan2(x)+tan4(x))2dx ? How do I evaluate the indefinite integral intx*sin(x)*tan(x)dx∫x⋅sin(x)⋅tan(x)dx ? See all questions in Integrals of Trigonometric Functions Impact of this question 24552 views around the world You can reuse this answer Creative Commons License