Angles Inscribed in a Semicircle
Author: Scott Farrar

Drag point C along the red semicircle AB.
What to you observe about angle ACB if you stay on the arc?
The measure of ACB is plotted with gray dots as you move point C.

Show Hint

See how close you got

Advanced: try dragging C along the 
semicircle that is NOT drawn.
(use your conjecture and the 
grey dots as a guide!!)

f(x) = 90
C = (18.606390096925345, 25.96204195855419)
A = (18.38724747880474, 22.14236224650396)
a = Segment(A, C)
B = (98.38724747880474, 22.14236224650396)
b = Segment(C, B)
α = Angle(A, C, B)
D: (x(C), α / (1 °))
c = Semicircle(A, B)
d = false
e = Semicircle(B, A)
g = false
h = Segment(A, B)