The firing of a revolutionary war cannon is used to open the local fourth of july festivities. the muzzle of the cannon barrel is 6 feet above ground level. the height of the cannon ball being fired from the revolutionary war cannon as a function of elapsed time is modeled by the function h(t) = –16t2 + 75t + 6, where h(t) is the height of the cannon ball in feet, and t is the elapsed time since firing in seconds. determine at approximately what elapsed time(s) the cannon ball will be at a height of 55 feet.