# Math Help - trig values

1. ## trig values

It's easy to see that is n is an odd positive integer, $\sin\Big(\frac{n \pi}{4}\Big) = \sin\Big(\frac{3n \pi}{4}\Big)$

and if n is an even positive integer, $\sin\Big(\frac{n \pi}{4}\Big) = -\sin\Big(\frac{3n \pi}{4}\Big)$

But how would you prove that?

2. By induction ?

Or else, use what you know about odd numbers : if n is even, n=(n-1)+1, where (n-1) is odd.
and use the addition formula for the sine function.