Prove that in any triangle, cash external angle is equal to the sum of the internal angles at the other two vertices.

Prove that in any triangle, cash external angle is equal to the sum of

1.	Prove that in any triangle, cash external angle is equal to the sum of the internal angles at the other two vertices.
Answer» Prove that in any triangle, cash external angle is equal to the sum of the internal angles at the other two vertices.