In the diagram,
Thus, m = 2 x 55∘^{\circ}∘ (is a bisector of obtuse
m = 110∘^{\circ}∘
n = 12\;\frac{1}{2}21 x 110∘^{\circ}∘ (angle at centre = 2 x angle at circum)
n = 55∘^{\circ}∘
m + n = 110 + 55 = 165∘^{\circ}∘
