
Problem 194. Area
of a Triangle, Semiperimeter, Exradius 
In the figure below, given a triangle
ABC of area S, s is the semiperimeter (a + b + c) / 2, and r_{a}
is the exradius relative to side BC. Prove that S = r_{a}.(s
 a).
View or post a solution

1. AREA OF A TRIANGLE:
Proposition:
The area of a triangle equals onehalf the product of the length
of a side and the length of the altitude to that side.

