CPM Homework Help : PC Problem 10-107

Challenge: Assuming no air resistance and a ball always thrown at $7$ feet above the ground with an initial velocity of $120$ ft/s, at what angle should the ball be released to go a maximum distance?
challenge problem

Hint 1:

This occurs when $y\left(t\right) = 0$ .

Solve for $t$ (in terms of $θ$ ) if $−16t^2 + 120\left(\sin θ\right)t + 7 = 0$ .

Hint 2:

The answer for t is not pretty, but substitute it into the equation $x\left(t\right) = 120\left(\cos θ\right)t$ .

You will need to graph this to determine when the distance is a maximum.