# Integral of Cos(5X)

Integral of cos(5x) along with its formula and proof with examples. Also learn how to calculate integration of cos(5x) with step by step examples.

Alan Walker-

Published on 2023-04-14

## Introduction to the integral of cos 5x

In calculus, the integral is a fundamental concept that assigns numbers to functions to define displacement, area, volume, and all those functions that contain a combination of tiny elements. It is categorized into two parts, definite integral and indefinite integral. The process of integration calculates the integrals. This process is defined as finding an antiderivative of a function.

Integrals can handle almost all functions, such as trigonometric, algebraic, exponential, logarithmic, etc. This article will teach you what is integral to a trigonometric function sine. You will also understand how to compute antiderivative of cos5x by using different integration techniques.

## What is the integral of cos5x?

The integral of cos(5x) is an antiderivative of the sine function which is equal to sin(5x)/5. It is also known as the reverse derivative of the sine function which is a trigonometric identity.

The cosine function is the ratio of the adjacent side to the hypotenuse of a triangle which is written as:

cos = adjacent side / hypotenuse

## Integral of cos 5x formula

The formula of integral of cos contains integral sign, coefficient of integration and the function as sine. It is denoted by ∫(cos(5x))dx. In mathematical form, the integral of cos(5x) is:

$\int \cos(5x)dx = \frac{\sin(5x)}{5} + c$

Where c is any constant involved, dx is the coefficient of integration and ∫ is the symbol of integral. The above formula can also be used to calculate the integral of cos(2x).

## How to evaluate integral of cos(5x) with respect to x?

The integral of cos5x is its antiderivative that can be calculated by using different integration techniques. In this article, we will discuss how to calculate integral of cosine by using:

1. Derivatives
2. Substitution Method
3. Definite Integral

## Integral of cos 5x by using derivatives

The derivative of a function calculates the rate of change, and integration is the process of finding the antiderivative of a function. Therefore, we can use the derivative to calculate the integral of a function. Let’s discuss calculating the integral of cos(5x) by using derivatives.

### Proof of integration of cos5x by using derivatives

Since we know that the integration is the reverse of the derivative. Therefore, we can calculate the integral of cos(5x) by using its derivative. For this, we have to look for some derivatives formulas or a formula that gives cos(5x) as the derivative of any function.

In derivative, we know that,

$\frac{d}{dx} \sin(5x) = 5\cos(5x)$

It means that the derivative of cos(5x) gives us sin(5x). Therefore, to obtain the integral of cosine,

$\frac{d}{dx} \sin(5x) = 5\cos(5x)$

Hence the integral of cos(5x) is equal to sin(5x)/5. It is written as:

$\int \cos(5x)dx = \frac{\sin(5x)}{5} + c{2}nbsp; Similarly, the integral of cos(4x) is equal to sin(4x)/4. ## Integration of cos5x by using substitution method The substitution method involves many trigonometric formulas. We can use these formulas to verify the integrals of different trigonometric functions such as sine, cosine, tangent, etc. Let’s understand how to prove the antiderivative of cos5x by using the substitution method. ### Proof of integration of cos 5x by using substitution method To prove the integral of cos(5x) by using substitution method calculator, suppose that:$y = \cos(5x)$Differentiating with respect to x,$\frac{dy}{dx} = - 5\sin(5x)$To calculate integral, we can write the above equation as:$dy = - 5\sin(5x)dx$By trigonometric identities, we know that sin(5x) = √1 - cos²5x. Then the above equation becomes,$dy = - 5\sqrt{1 - \cos^2(5x)}.dx$Now, substituting the value of cos2 5x, such as:$dy = - 5\sqrt{1 – y^2}. dx$Multiplying both sides by cos(5x),$-\frac{\cos(5x)dy}{5\sqrt{1 - y^2}} = \cos(5x) dx$Again substitute cos(5x) = y on the left side.$-\frac{y dy}{5\sqrt{1 - y^2}}= \cos(5x)dx$Integrating on both sides by applying integral,$-\int \frac{y dy}{5\sqrt{1 - y^2}} = ∫\cos(5x) dx$Let 1 - y² = u. Then$-2y dy = du\quad\text{or}\quad y dy = -\frac{1}{2}du$Then the above left-hand side integral becomes,$\frac{-1}{2}\int \frac{-1}{5\sqrt{u}} du =\int \cos(5x) dx\frac{1}{2} \int \frac{u^{-1/2}}{5} du = \int \cos(5x)dx$Since the power rule of integration is$\int x^n dx = \frac{x^{n+1}}{(n+1)}+C$Therefore, by using this formula we get,$\frac{u^{1/2}}{5} + C =\int \cos(5x)dx$Again substituting u = 1 - y², we get$\frac{(1 - y^2)^{1/2}}{5} + C = \int \cos(5x)dx$And again Substitute y = cos(5x) here,$\frac{\left(1 - \cos^2(5x)\right)^{1/2}}{5} + C =\int \cos(5x) dx\frac{\left(\sin^2(5x)\right)^{1/2}}{5} + C =\int \cos(5x)dx\frac{\sin(5x)}{5} + C = \int\cos(5x) dx$Hence the integral of cos5x is sin(5x)/5. For a non-linear integral, you can use trig-substitution calculator as it provide you an easy and quick solution. ## Integration of cos 5x by using definite integral The definite integral is a type of integral that calculates the area of a curve by using infinitesimal area elements between two points. The definite integral can be written as:$\int^b_a f(x) dx = F(b) – F(a)$Let’s understand the verification of the integral of cos 5x by using the definite integral. ### Proof of integration of cos5x by using definite integral To evaluate integral of cos(5x) with respect to x by using a definite integral, we can use the interval from 0 to π or 0 to π/2. Let’s compute the integral of cos(5x) from 0 to π. For this we can write the integral as:$\int^\pi_0 \cos(5x) dx = \left|\frac{\sin(5x)}{5}\right|^\pi_0$Now, substituting the limit in the given function.$\int^\pi_0 \cos(5x) dx = \frac{\sin(5π)}{5} – \frac{\sin(0)}{5}$Since sin 0 is equal to 0 and sin π is equal to 0, therefore,$\int^\pi_0 \cos(5x) dx = 0$Which is the calculation of the definite integral of cos(5x). Now to calculate the integral of cos(5x) between the interval 0 to π/2, we just have to replace π by π/2. Therefore,$\int^{\frac{\pi}{2}}_0 \cos(5x)dx = \left|\frac{\sin(5x)}{5}\right|^{\frac{\pi}{2}}_0$Now,$\int^{\frac{\pi}{2}}_0 \cos(5x)dx=\frac{\sin(5π/2)}{5} – \frac{\sin(0)}{5}$Since sin 0 is equal to 0 and sin π/2 is equal to 1, therefore,$\int^{\frac{\pi}{2}}_0 \cos(5x)dx = 1\$

Therefore, the definite integral of cos(5x) is equal to 1.