a = 30 (slider from 0 to 90, step 1)
V = 21.6 (slider from 0 to 40, step 0.1)
h(x) = -5 x^(2) + V sin(a 3.141592653589793 / 180) x
d(x) = V cos(a 3.141592653589793 / 180) x
O = (0, -5)
R = (300, -5)
b = Segment(O, R)
t = Point(b)
B: (d(x(t) / 20), h(x(t) / 20))
loc1 = Locus(B, t)
c = Circle(B, 2)
text1: "t = " + (x(t) / 20) + " s"