Find the value of each variable. The dot represents the center of the circle Lines that appeartangent are tangent.

The measure if an inscribed angle is half the measure of the intercepted arc
Angle a is an inscribed angle and the intercepted arc is 50°. Then, the measure of angle a is:
[tex]\begin{gathered} a=\frac{1}{2}(50) \\ \\ a=25 \end{gathered}[/tex]Line m is tangent, then it is perpendicular to the diameter of the circle. It forms a angle of 90° with the diameter of the circle.
The sum of angles a and b is 90°:
[tex]\begin{gathered} a+b=90 \\ b=90-a \\ b=90-25 \\ b=65 \end{gathered}[/tex]Angle c is an inscribed angle and the intercepted arc is 82°. Then, the measure of angle c is:
[tex]\begin{gathered} c=\frac{1}{2}(82) \\ \\ c=41 \end{gathered}[/tex]Then, you have the next values for the variables:
a=25°
b=65°
c=41°