# Evaluate the integral \int \cos^4(4x+5) \,dx

## Question:

Evaluate the integral {eq}\int \cos^4(4x+5) \,dx {/eq}

## Evaluating Integrals:

In this question, we have to evaluate the given indefinite integral. Here we use reduction formula and some trigonometric identity to evaluate the given integral .

{eq}\int \cos^4(4x+5) \,dx {/eq}

Let {eq}4x+5=u {/eq}

{eq}dx = du/4 {/eq}

So we will get:

{eq}\frac{1}{4} \int \cos^4(u) \,du {/eq}

{eq}\cos...

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