A professional stunt performer at a theme park dives off a tower 21 m high into the water. His height above the ground at time t seconds is given by the equation h= -4.9t^2 + 21. a) How long does it take to reach the halfway mark?

b) How long does it take to reach the water?

c) Compare the times in (a) and (b). Explain why the time at the bottom is not twice the time at the halfway point.