Geometry Practice Test 2

In figure a° +∠EBC = π − b°
∠EBC = π − b° − a° [sum of two opposite
interior angles is equal to the exterior angle].
and ∠EBA + C° = x°
∠EBA = x° − C° ......(i)
∠EBA + ∠EBC = 180° [linear pair]
∠EBA = 180° − (π − b° − a°) ......(ii)
Comparing (i) and (ii),
x° − c° = 180° − π + b° + a°
x° = a° + b° + c°