The sum measure of all angles of a traingle is180 degree proved it

Question

How the sum of all angles of a traingle is 180^o

Answer 1

Start with a rectangle. Convince yourself that the internal angles of a rectangle are 360 degrees.

Now draw a diagonal in the rectangle and then look at the angles that makeup the two triangles that you formed with the diagonal.

Hope that helps!

Answer 2

Start on one of the sides and walk around the triangle. At each corner you will turn through an angle which is 180 degrees - the angle at that corner. When you get to the starting point, you will have turned a total of 360 degrees. So....assign letters to each angle--eg A,B, and C.

Add up the 3 turns and set equal to 360:

(180-A) + (180-B) + (180 - C) = 360

Solve this for A+B+C, and you will see that the total is 180