B=p(x,y)

eq1 = Parabola = y^2=4*P*x ,P=1

eq2=directrix

P = 1 (slider from -5 to 5)
eq1: (y * y) = ((4 * P) * x)
eq2: x = -1
A = (1, 0)
B = Point(eq1)
f = OrthogonalLine(B, eq2)
C = Intersect(eq2, f)
distanceCB = Distance(C, B)
Midpoint(C, B)
distanceBA = Distance(B, A)
Midpoint(B, A)
TextBA: Name[B] + (Name[A]) + " = " + distanceBA
g = Segment(A, B)
TextCB: "" + C + Name[B] + " = " + distanceCB + ""
a = Distance(C, B)
Midpoint(C, B)
text1: Name[C] + (Name[B]) + " = " + a
h = Segment(C, B)