I already know what a and b are i just need help on c

Answer:
180⁰
Step-by-step explanation:
Since the angle of straight line is 180⁰
Answer:
A and B = 180 degrees
Step-by-step explanation:
this is because a circle is 360 and a line wich would be cutting the line in half is 180. so the two andles must add up to 180 degrees.