The Law of Sines - Proof

Given is an arbitrary triangle with sides , and and angles , and . Prove that , where is the diameter of the circle through the vertices.
  • Drag the orange vertices in counterclockwise direction as far as they can go. 
  • Use the resulting right triangles to write trigonometric ratios involving the green side, the red side , and the green angle.
  • Experiment with different triangles.