ohhhh i see now. the t in the H equation is the time to get to maximum height, which is half of the t in the R equation. so it would really be (1/2)(v0sinθ)(t/2) = (v0cosθ)(t) which gives tanθ = 4 so θ = 75.9° (A). Thanks so much!
Homework Statement
A cannonball is launched with initial velocity of magnitude v0 over a horizontal surface. At what minimum angle θmin above the horizontal should the cannonball be launched so that it rises to a height H which is larger than the horizontal distance R that it will travel...