Question

Verify experimentally the sum of angle of triangle is 180°​

Answer 1

Answer:

Draw line a through points A and B. Draw line b through point C and parallel to line a. Since lines a and b are parallel, <)BAC = <)B'CA and <)ABC = <)BCA'. It is obvious that <)B'CA + <)ACB + <)BCA' = 180 degrees