find the period of a trigonometric function I've found the period of this trigonometric function,
$$y=\sin^n(x)+\cos^n(x)$$.

when n （$n\neq2$）is odd, the period is $2\pi$, 

when n is even, the period is $\frac{\pi}{2}$.

but how to proof it?
Consider the periods of both terms, the period of the sum is the least common multiple of both.

You could express the sine and cosine using complex exponentials, often that makes trigonometric identities trivial.
Consider the periods of both terms, the period of the sum is the least common multiple of both.

You could express the sine and cosine using complex exponentials, often that makes trigonometric identities trivial.