What is the integral of (cos(x))^3 ?

The integral of (cos(x))^3 is sin(x)-(sin^3(x))/3+C

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integral of (cos(x))^3

integral

(cos (x))^{3}

sin (x) - \frac{sin ^{3} ( x )}{3} + C

Solution steps

\int (cos (x))^{3} d x

Simplify

= \int cos^{3} (x) d x

Rewrite using trig identities

= \int (1 - sin^{2} (x)) cos (x) d x

Apply u-substitution

= \int 1 - u^{2} d u

Apply the Sum Rule:

\int f (x) \pm g (x) d x = \int f (x) d x \pm \int g (x) d x

= \int 1 d u - \int u^{2} d u

\int 1 d u = u

\int u^{2} d u = \frac{u ^{3}}{3}

= u - \frac{u ^{3}}{3}

Substitute back

u = sin (x)

= sin (x) - \frac{sin ^{3} ( x )}{3}

Add a constant to the solution

= sin (x) - \frac{sin ^{3} ( x )}{3} + C

What is the integral of (cos(x))^3 ?
The integral of (cos(x))^3 is sin(x)-(sin^3(x))/3+C