1. The problem statement, all variables and given/known data A projectile is fired with speed v_0 (velocity subscript zero) at an angle θ from the horizontal as shown in the figure Consider your advice to an artillery officer who has the following problem. From his current position, he must shoot over a hill of height H at a target on the other side, which has the same elevation as his gun. He knows from his accurate map both the bearing and the distance R to the target and also that the hill is halfway to the target. To shoot as accurately as possible, he wants the projectile to just barely pass above the hill. Find the angle θ above the horizontal at which the projectile should be fired. Express your answer in terms of H and R. 2. Relevant equations v_0x = v_0 * cosθ v_0y = v_0 * sinθ tanθ = (sinθ)/(cosθ) 3. My attempt at a solution According to the description, the hill is "halfway to the target". Thus, the highest point is at R/2. I can then make a triangle with H as the opposite side and (R/2) as the adjacent side. Using trig, I get tanθ = opp/adj = H/(R/2) = 2H/R. My final answer is thus θ = arctan(2H/R). The answer above is incorrect and I already know what the correct answer is. What I don't understand is what's wrong with the above method? Solving it is much simpler and makes perfect sense to me. Thank you all very much.