Question 878962
h=-0.0425d^2+3.57d
a)d(-.0425d + 3.57) = 0, d = 3.57/.0425 = 84m is the width at the base
b)max height is at d = 42m
h(42) ={{{-0.0425(42)^2+3.57*42 }}} = 74.97m