ANSWER:
c. 133°
STEP-BY-STEP EXPLANATION:
We have that there is a chord that divides the circle in two equal parts because it passes through the middle of the circle. Since it is half of the circle, the arc is 180°, we can see that this arc is the sum of the angles a + b, this angle must measure half of 180°, therefore:
[tex]a\degree+b\degree=\frac{180\degree}{2}=90\degree[/tex]Now the angle c° must measure half of the 86° arc, therefore:
[tex]\begin{gathered} c\degree=\frac{86\degree}{2}=43\degree \\ \end{gathered}[/tex]That means that a° + b° + c° is equal to:
[tex]a°+b°+c°=90+43=133\degree[/tex]Therefore, the correct answer is c. 133°