1. The problem statement, all variables and given/known data A rock is thrown horizontally from the top of a 20-m high cliff and strikes the ground at an angle of 45 degrees. With what speed was it thrown? 2. Relevant equations R = V2/g*sin(2theta) v2 = (v0*sin(theta))2 - 2gy 3. The attempt at a solution I have 2 unknowns no matter what equation I try to use. I've tried to get it down to one unknown, but I keep getting the wrong answer..