some proofs for triangle theorems

In the following, only Euclidean geometryMathworldPlanetmath is considered.

The sum of three angles A, B, and C of a triangle is A+B+C=180.

The following triangle shows how the angles can be found to make a half revolution, which equals 180.

The area A=rs where s is the semiperimeter s=a+b+c2 and r is the radius of the inscribed circle can be proven by creating the triangles BAO, BCO, and ACO from the original triangle ABC, where O is the center of the inscribed circle.


Title some proofs for triangle theorems
Canonical name SomeProofsForTriangleTheorems
Date of creation 2013-03-22 14:03:55
Last modified on 2013-03-22 14:03:55
Owner Wkbj79 (1863)
Last modified by Wkbj79 (1863)
Numerical id 13
Author Wkbj79 (1863)
Entry type Proof
Classification msc 51-00