Question

prove that sum of angles of triangle is equal to 180 degree ​

Answer 1

Step-by-step explanation:

Theorem. If ABC is a triangle then <)ABC + <)BCA + <)CAB = 180 degrees.

Proof. Draw line a through points A and B. Draw line b through point C and parallel to line a.

Lemma. ...

Proof. ...

Definition.

Answer 2

Answer

According to the figure in attachment;

1 + 2 = 4 (exterior angle property)

4 = 180 - 3 (linear pair)

=> 1 + 2 = 180 - 3

=> 1 + 2 + 3 = 180

HENCE PROVED