Hello, I am stuck on this problem involving the parametrizing of two surfaces :

Find a parametrization of the following curve:

The intersection of the plane with the sphere

$\displaystyle r(t)= < ? , 7 , ?>$

I have gotten the second component which is simply 7, but that's as far as i have gotten, i know that the first and third are going to involve cos(t) and sin(t) respectivly, but how do i go about solving them?

Thanks again!!