If you get the answer also tell me how you got it , i'm putting a lot of points for this one

Find the derivative of the function

Larissa dives into a pool that is 8 feet deep. she touches the bottom of the pool with her hands 6 feet horizontally from the point at which she entered the water. what is the approximate angle of elevation from the point on the bottom of the pool where she touched to her entry point? 36.9° 41.4° 48.6° 53.1°

Tangent ? ) × cos /2 +? ) > 0. the answer is that cos ? < 0. i forgot to put the minus before. i get confusermd when i see questions similar to this when the radian is negative such as /2 i cant seem to solve it