1. The problem statement, all variables and given/known data A shell is fired from a cliff that is 36m above a horizontal plane. the muzzle speed of the shell is 80.0m/s and it is fired at an elevation of 25 degrees above the horizontal. a) show that thetime of flight is 7.84 seconds. 2. Relevant equations dy = viy(t) + 0.5(a)(t2) 3. The attempt at a solution i got yp to 0 = 0.5(-9.8)(t2) + (80sin25)(t) - (36) now, i know that i msut use the quadratic eq. but why is that -36m wrong in the equation, in my corrections it says it should be a positive 36 and be a -36 when it is on the left side of the equation. How do i know when to make the vertical displacement negative?