The value of $\int \frac {1}{1+ Cos \; 8x}dx$ is
- $\frac {\tan\, 8x}{8}+C$
- $\frac {\tan\,2x}{8}+C$
- $\frac {\tan\,4x}{8}+C$
- $\frac {\tan\,4x}{4}+C$
The Correct Option is C
Solution and Explanation
$ = \int \frac{1}{2 \cos^{2} 4x} dx$
$ x = \frac{1}{2} \int \sec^{2} 4 x dx$
$ = \frac{1}{2} \frac{\tan 4x}{4} + c $
$ = \frac{\tan4x}{8} +c $
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Concepts Used:
Methods of Integration
Given below is the list of the different methods of integration that are useful in simplifying integration problems:
Integration by Parts:
If f(x) and g(x) are two functions and their product is to be integrated, then the formula to integrate f(x).g(x) using by parts method is:
∫f(x).g(x) dx = f(x) ∫g(x) dx − ∫(f′(x) [ ∫g(x) dx)]dx + C
Here f(x) is the first function and g(x) is the second function.
Method of Integration Using Partial Fractions:
The formula to integrate rational functions of the form f(x)/g(x) is:
∫[f(x)/g(x)]dx = ∫[p(x)/q(x)]dx + ∫[r(x)/s(x)]dx
where
f(x)/g(x) = p(x)/q(x) + r(x)/s(x) and
g(x) = q(x).s(x)
Integration by Substitution Method
Hence the formula for integration using the substitution method becomes:
∫g(f(x)) dx = ∫g(u)/h(u) du
Integration by Decomposition
Reverse Chain Rule
This method of integration is used when the integration is of the form ∫g'(f(x)) f'(x) dx. In this case, the integral is given by,
∫g'(f(x)) f'(x) dx = g(f(x)) + C
Integration Using Trigonometric Identities
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