y = 12

This is the sketch associated with problem 30 on the 2010
HS geometry test from the math contest at UH.

The question gave us the total circumference of 60, and 
asked for the length of the hypotenuse. Adjust the value of r
to force the triangle circumference to be 60, and then read
off the length of the hypotenuse.

r = 15.34 (slider from 12 to 20, step 0.01)
A = (0, 0)
f(x) = 12.0
c = Circle(A, r)
B: (sqrt(r^(2.0) - 144.0), 12.0)
C: (-x(B), 12.0)
D: (-(r), 0.0)
E: (r, 0.0)
a = Segment(D, C)
b = Segment(C, E)
d = Segment(E, D)
text1: "triangle circumference " + (a + b + d)
poly1, e, d_1, c_1 = Polygon(D, C, E)
F: (x(C), 0.0)
g = Segment(C, F)
α = Angle(D, C, E)
β = Angle(E, F, C)