Question

In the figure below, 1 and 2 are adjacent angles:



Write an indirect proof proving that the sum of 1 and 2 is 180°.

Answer 1

help?

Answer 2

???

Answer 3

180 - angle 1 = angle 2 (straight line)
180 = angle 1 + angle 2 (bring angle 1 to the other side of the equation)

Answer 4

Assume that m<1+m<2 is not equal to 180. CA and CB are opposite rays. <1 and <2 are adjacent angles . 1 and < 2 are supplementary => m<1+m<2 = 180 . => the assumption m<1+m<2 is not 180 is false. =>the sum of two adjacent angles is 180.