Posted by **Brian** on Saturday, March 10, 2012 at 2:40pm.

A projectile is launched from a platform 20 feet high with an initial velocity of 72 feet per second,

The height h of the projectile at t seconds after launch is given by h = –16t2 + 72t + 20 feet.

(a) How many seconds after launch does the projectile attain maximum height? Show work.

(b) What is the maximum height? Show work.