Answer:
First at
5/4 +(√3)/2s
then at
5/4 -(√3)/2
Step-by-step explanation:
h(t) = -16t^2 + 40t + 47 = 60
so all we need to do it find the solution of the equation
so 16t^2 - 40t + 13 = 0
and as we know
root = (-b+-√(b^2-4ac))/2a
so
root = 5/4 +-(√3)/2