Use the quadratic formula to solve the equation. if necessary, round to the nearest hundredth. a rocket is launched from atop a 76-foot cliff with an initial velocity of 135 ft/s. a. substitute the values into the vertical motion formula h=-16t2+vt+c let h = 0. b. use the quadratic formula find out how long the rocket will take to hit the ground after it is launched. round to the nearest tenth of a second.