# Simple integral

1. Dec 1, 2008

### leopard

Can somebody explain to me why
$$\int^{1}_{0}sin( \pi x) sin (n \pi x) dx$$ equals 1 if n = 1 and 0 for n >= 2? (n is an integer)

Last edited: Dec 1, 2008
2. Dec 1, 2008

### neo86

Just to give a hint: trigonometric addition formulas...
If this isn't sufficient to solve it, ask again.