prove that the sum of a triangle is equal to 180° please answer it fast . thank you!!!!
Share
prove that the sum of a triangle is equal to 180° please answer it fast . thank you!!!!
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
We draw a line parallel to AB that passes
through point C.
Angles C and C' are vertical angles,
therefore ∠C = ∠C'.
Angles B and B' are corresponding angles,
therefore ∠B = ∠B'.
Angles A and A' are corresponding angles, therefore ∠A = ∠A'.
So, the angle sum ∠A + ∠B + ∠C is equal to the angle sum ∠A' + ∠B' + ∠C'.
The three angles A', B', and C' form together a straight angle (they are along the line l).
So, their angle sum is 180°. But then the angle sum ∠A + ∠B + ∠C must also be 180°.
hope it helps ✌