perimeter = 7 (slider from 1 to 7, step 1)
a: x + y = perimeter
A = Point(a)
b = OrthogonalLine(A, yAxis)
c = OrthogonalLine(A, xAxis)
B = Intersect(yAxis, b)
C = Intersect(yAxis, xAxis)
D = Intersect(xAxis, c)
poly1, b_1, c_1, d, a_1 = Polygon(B, C, D, A)
Textpoly1: "Area " + (Name[B]) + (Name[C]) + (Name[D]) + (Name[A]) + " = " + poly1
E = Intersect(yAxis, a)
F = Intersect(xAxis, a)
Area: (x(A), poly1)
text1: "perimeter = " + perimeter
f = Segment(E, F)