An explanation of the star angles

The full degree rotation of a circle is 360.

If O is the center of the circle, then angle AOB, angle BOC, angle COD, angle DOE, and angle EOA are the central angles. The measures of the intercepted arcs are equal to the measures of the central angles. The sum of the angles is 360 degrees.

 

Each angle on the circle is an inscribed angle which is equal to half the measure of the intercepted arc. The sum of the measures of the angles, A + B + C + D + E is equal to half of 360 which is 180.

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