What is the integral of cos^2(3x) ?

The integral of cos^2(3x) is 1/2 (x+1/6 sin(6x))+C

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

integral of cos^2(3x)

integral

cos^{2} (3 x)

\frac{1}{2} (x + \frac{1}{6} sin (6 x)) + C

Solution steps

\int cos^{2} (3 x) d x

Rewrite using trig identities

= \int \frac{1}{2} (1 + cos (6 x)) d x

Take the constant out:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= \frac{1}{2} \cdot \int 1 + cos (6 x) d x

Apply the Sum Rule:

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

= \frac{1}{2} (\int 1 d x + \int cos (6 x) d x)

\int 1 d x = x

\int cos (6 x) d x = \frac{1}{6} sin (6 x)

= \frac{1}{2} (x + \frac{1}{6} sin (6 x))

Add a constant to the solution

= \frac{1}{2} (x + \frac{1}{6} sin (6 x)) + C

What is the integral of cos^2(3x) ?
The integral of cos^2(3x) is 1/2 (x+1/6 sin(6x))+C