Answer:
a = 35, b = 40, c = 17.5
Step-by-step explanation:
The sum of the 3 arcs on the semicircle above the diameter = 180° , that is
65 + 80 + a = 180
145 + a = 180 ( subtract 145 from both sides )
a = 35
The inscribed angles b and c are half the measures of their intercepted arcs
b = [tex]\frac{1}{2}[/tex] × 80 = 40
c = [tex]\frac{1}{2}[/tex] × 35 = 17.5
