In the diagram, triangle MNR is inscribed in circle MNR, and line PQ is a straight line. ∠MRN = 41 and = 141, find ∠QNR
- 39º
-
80º
- 110º
- 141º
The correct answer is: B
Explanation
The exterior angle theorem states that the measure of each exterior angle of a triangle is equal to the sum of the opposite and non-adjacent interior angles.
∠M = ∠R + ∠N
→ 141 = 41 + ∠N
∠N = 141 - 41 = 100º
∠QNR = 180 - 100 → 80º