Please can somebody help.

The $\displaystyle \sim$ relation on $\displaystyle \Re$ is defined by x $\displaystyle \sim$y if and only if $\displaystyle \sin ^2 x + \cos^2 y = 1$ .

Show that $\displaystyle \sim$ is an equivalence relation on $\displaystyle \Re$.

Your help would be much appreciated.

riptorn70.