Amodel airplane is shot up from a platform 1 foot above the ground with an initial upward velocity of 56 feet per second. the hight of the airplane above ground after t seconds is given by the equation h=-16t^2+56t+1 where h is the hight of the airplane in feet and t is the time in seconds after it is launched. approximately how long does it take the airplane to reach its maximum height?
a)0.3 seconds
b)1.8 seconds
c)3.5 seconds
d)6.9 seconds