Let's analyze the question to determine the correct term for an arc that measures 180 degrees.
1. Understanding Arcs in Circles:
- A circle has a total angular measure of [tex]\(360^{\circ}\)[/tex].
- An arc is any portion of the circle's circumference.
2. Types of Arcs:
- A minor arc is an arc measuring less than [tex]\(180^{\circ}\)[/tex].
- A major arc is an arc measuring more than [tex]\(180^{\circ}\)[/tex].
- A semicircle is an arc that measures exactly [tex]\(180^{\circ}\)[/tex].
3. Identifying the Given Arc:
- The problem specifies an arc that measures exactly [tex]\(180^{\circ}\)[/tex].
- According to our understanding, an arc of [tex]\(180^{\circ}\)[/tex] divides the circle into two equal parts.
4. Conclusion:
- Since a semicircle by definition is an arc that measures [tex]\(180^{\circ}\)[/tex], we identify the term for the given measure of an arc.
Thus, the arc that measures [tex]\(180^{\circ}\)[/tex] is called a semicircle.
The correct answer is:
B. semicircle
