Explain how you can use the inscribed angle theorem to justify its second corollary, that an angle inscribed in a semicircle is a right angle.

Answer:

A circle measures 360°, so a semicircle (which is half the circle) measures 180°. According to the inscribed angle theorem, the measure of an inscribed angle is half the measure of its intercepted arc. Since an angle inscribed in a semicircle intercepts an arc of 180°, the measure of the inscribed angle is half of 180°, which is 90°. Therefore, the angle is a right angle.