What is the integral of 2/(1+cos^2(x)) ?

The integral of 2/(1+cos^2(x)) is sqrt(2)arctan(1/(sqrt(2))tan(x))+C

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integral of 2/(1+cos^2(x))

\int \frac{2}{1 + cos ^{2} ( x )} d x

2 arctan (\frac{1}{2} tan (x)) + C

Solution steps

\int \frac{2}{1 + cos ^{2} ( x )} d x

Take the constant out:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= 2 \cdot \int \frac{1}{1 + cos ^{2} ( x )} d x

Rewrite using trig identities

= 2 \cdot \int \frac{2}{cos ( 2 x ) + 3} d x

Take the constant out:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= 2 \cdot 2 \cdot \int \frac{1}{cos ( 2 x ) + 3} d x

Apply u-substitution

= 2 \cdot 2 \cdot \int \frac{1}{2 ( cos ( u ) + 3 )} d u

Take the constant out:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= 2 \cdot 2 \cdot \frac{1}{2} \cdot \int \frac{1}{cos ( u ) + 3} d u

Apply u-substitution

= 2 \cdot 2 \cdot \frac{1}{2} \cdot \int \frac{1}{v ^{2} + 2} d v

Apply Integral Substitution

= 2 \cdot 2 \cdot \frac{1}{2} \cdot \int \frac{1}{2 ( w ^{2} + 1 )} d w

Take the constant out:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= 2 \cdot 2 \cdot \frac{1}{2} \cdot \frac{1}{2} \cdot \int \frac{1}{w ^{2} + 1} d w

Use the common integral:

\int \frac{1}{w ^{2} + 1} d w = arctan (w)

= 2 \cdot 2 \cdot \frac{1}{2} \cdot \frac{1}{2} arctan (w)

Substitute back

= 2 \cdot 2 \cdot \frac{1}{2} \cdot \frac{1}{2} arctan (\frac{tan ( \frac{2 x}{2} )}{2})

Simplify

2 \cdot 2 \cdot \frac{1}{2} \cdot \frac{1}{2} arctan (\frac{tan ( \frac{2 x}{2} )}{2}) : 2 arctan (\frac{1}{2} tan (x))

= 2 arctan (\frac{1}{2} tan (x))

Add a constant to the solution

= 2 arctan (\frac{1}{2} tan (x)) + C

What is the integral of 2/(1+cos^2(x)) ?
The integral of 2/(1+cos^2(x)) is sqrt(2)arctan(1/(sqrt(2))tan(x))+C