What is the integral of sin(20x)cos(15x) ?

The integral of sin(20x)cos(15x) is 1/2 (-1/35 cos(35x)-1/5 cos(5x))+C

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integral of sin(20x)cos(15x)

\int sin (20 x) cos (15 x) d x

\frac{1}{2} (- \frac{1}{35} cos (35 x) - \frac{1}{5} cos (5 x)) + C

Solution steps

\int sin (20 x) cos (15 x) d x

Use the following identity:

cos (t) sin (s) = \frac{sin ( s + t ) + sin ( s - t )}{2}

= \int \frac{sin ( 20 x + 15 x ) + sin ( 20 x - 15 x )}{2} d x

Take the constant out:

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

= \frac{1}{2} \cdot \int sin (20 x + 15 x) + sin (20 x - 15 x) d x

Simplify

= \frac{1}{2} \cdot \int sin (35 x) + sin (5 x) d x

Apply the Sum Rule:

\int f (x) \pm g (x) d x = \int f (x) d x \pm \int g (x) d x

= \frac{1}{2} (\int sin (35 x) d x + \int sin (5 x) d x)

\int sin (35 x) d x = - \frac{1}{35} cos (35 x)

\int sin (5 x) d x = - \frac{1}{5} cos (5 x)

= \frac{1}{2} (- \frac{1}{35} cos (35 x) - \frac{1}{5} cos (5 x))

Add a constant to the solution

= \frac{1}{2} (- \frac{1}{35} cos (35 x) - \frac{1}{5} cos (5 x)) + C

\int (3^{x} + \frac{2}{x}) d x

\int_{2}^{5} \frac{1}{x - 1} d x

\int x^{2} (2 x^{3} + 4)^{5} d x

\int \frac{x}{k} d x

x^{2} + x^{3} 1

What is the integral of sin(20x)cos(15x) ?
The integral of sin(20x)cos(15x) is 1/2 (-1/35 cos(35x)-1/5 cos(5x))+C