# Trigonometric integral

• Jun 6th 2011, 08:58 AM
hurz
Trigonometric integral
$\int sin(x)cos(nx)dx$ where n is a positive entire
Thank's.
• Jun 6th 2011, 09:01 AM
General
$\displaystyle sin(A)cos(B)=\frac{sin(A-B) + sin(A+B)}{2}$
• Jun 6th 2011, 09:03 AM
FernandoRevilla
Use $2\sin mx\cos nx=\sin (m+n)x+\sin (m-n)x$ .

Edited: Sorry, I didn't see General's post.
• Jun 6th 2011, 09:07 AM
Ackbeet
You could also integrate by parts twice and solve for the original integral.