From the above diagram we can conclude that ~
Angle c = Angle a (Alternate interior Angle pair)
Angle d = Angle b (Alternate interior Angle pair)
and,
because their opposite sides are equal.
now, according to linear pair property ~
- Angle a + Angle b + 65° = 180°
replacing Angle a with Angle c and Angle d with Angle b, because they are equal to one another ~
- Angle c + Angle d + 65° = 180°
(because Angle c = Angle d)
- Angle c = 57.5° = Angle d
So,
- Angle a = Angle c = 57.5°
- Angle b = Angle d = 57.5°