A half circle contains 180 degrees. The complete circle is divided into two equal parts, so when you take half of that circle, you end up with half of the total degrees.
To put it simply, a full circle measures 360 degrees. When you divide this measurement by two, you get:
360 degrees ÷ 2 = 180 degrees
This means that if you were to draw a straight line from one side of the circle to the other, creating a semicircle, the angle formed at the center of that semicircle would be 180 degrees. This concept is foundational in geometry and is often used in various applications, such as in the study of angles, arcs, and trigonometry.