Question:

Find the integrals of the function: \(\frac{sin2 x}{1+cos x}\)

Updated On: Oct 11, 2023
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Solution and Explanation

\(\frac{sin2 x}{1+cos x}\) \(= \frac{(2sin   (\frac{x}{2})  cos \frac{x}{2})^2 }{2cos^2   (\frac{x}{2})}     \)             \( [sin x = 2sin   (\frac{x}{2})   cos   (\frac{x}{2})  ; cos x = 2cos^2   (\frac{x}{2})  -1]\)

\(= \frac{4sin^2 \frac{x}{2} cos^2   (\frac{x}{2})  }{ 2cos^2\frac{x}{2}} \)

\(= 2sin^2   (\frac{x}{2})\)
= 1-cos x

∴ ∫\(\frac{sin2 x}{1+cos x}\) dx = ∫(1-cos x)dx

= x - sin x+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