r = 1 (slider from -1 to 1, step 0.01)
g: (r * (4 - sqrt(4 + (45 / 16 * r^(2)))) / (16 - (15 / 4 * r^(2))))
h: sqrt(1 - g^(2))
a: (g * x) + ((1 / 2 * h) * y) - r = 0