A professional stunt performer at a theme park dives off a tower 21metres high into the water. His height above the ground at time tseconds is given by the equation h=-4.9t^2+21

Question

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

drwls · Answer

Solve the equation 10.5 = -4.9 t^2 + 21 which can be rewritten t^2 = 10.5/4.9 = 2.14 s^2 t = sqrt2.14 = ___ s