I'm having difficulty understanding how to properly change these bounds of integration. When I set up the bounds, which x or y bound is supposed to depend on the other? 

$$\int\_{0}^{\pi/2}\int\_{0}^{\cos(y)}7\cos(y) dxdy$$

I came up with below, but I believe my method was flawed or I misunderstood which operations need to be swapped in order to properly set each minimum and maximum. I feel that I may be mixing up general trigonometric rules with setting up bounds.

$$\int\_{0}^{\pi/2}\int\_{\arccos(0)}^{\arccos(x)}7\cos(y) dydx$$