To determine the angle measure of a semicircle, let's consider the properties of a circle.
1. A full circle is measured as 360 degrees.
2. A semicircle represents exactly half of a full circle because "semi" means half.
So, to find the angle measure of a semicircle, we need to divide the total angle measure of a full circle by 2:
[tex]\[ \text{Angle of a semicircle} = \frac{360^\circ}{2} \][/tex]
When you perform this division:
[tex]\[ \frac{360^\circ}{2} = 180^\circ \][/tex]
Therefore, the angle measure of a semicircle is 180 degrees.
So, the correct answer is:
C. 180°
