Question

given angle 1 = angle 3, angle 4 supplementary to angle 1, angle 2 supplementary to angle 3. what is angle 4 = angle 2

Answer 1

1.,,, <1 +<2 = 180,,,,,given supplementary
.
2.,,, <3 +<4 = 180,,,,,given supplementary
.
3.,,, <2 = 180- <1,,,,,subst postulate
.
4.,,, <3 = 180- <4,,,,,subst postulate
.


5,,,<2 = <3,,,,,,,,,,,,,,given
.
6,,,180-<1 = 180-<4,,,,,,substitution
.
7,,,<1 = <4,,,,,,substraction and multiplication postulate
.
.
Note: There is a Theorem that " if 2 angles are supplements of equal angles,,,then the two angles are congruent"