Triangle Inscribed - Circle Problem

Category: Trigonometry, Plane Geometry

"Published in Newark, California, USA"

If R is the radius of a circle circumscribed about the triangle ABC, show that 

Photo by Math Principles in Everyday Life

Hint: ∠BAC = ∠DOC

Solution:

Consider ∆DOC

Consider ∆ABC and apply Sine Law, we have

but

Therefore,