# Evaluate: ∫ 2 Cos 2 X − Cos 2 X Cos 2 X D X - Mathematics

Sum

Evaluate:

$\int\frac{2 \cos^2 x - \cos 2x}{\cos^2 x}dx$

#### Solution

$\int\left( \frac{2 \cos^2 x - \cos 2x}{\cos^2 x} \right)dx$
$= \int\left( \frac{2 \cos^2 x - \left( 2 \cos^2 x - 1 \right)}{\cos^2 x} \right)dx \left[ \because \cos 2x = 2 \cos^2 x - 1 \right]$
$= \int \sec^2\text{ x dx}$
$= \ \text{tan x} + C$

Concept: Evaluation of Definite Integrals by Substitution
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#### APPEARS IN

RD Sharma Class 12 Maths
Chapter 19 Indefinite Integrals
Exercise 19.1 | Q 5.2 | Page 4