Video covers four Theorems that pertain to Inscribed angles . The four Theorems are as follows.
Theorem: The measure of an inscribed angle is one half the measure of its intercepted arc
Theorem: If two inscribed angles of a circle intercept the same arc, then the angles are congruent
Theorem: If a right angle is inscribed in a circle, then the hypotenuse is a diameter of the circle.
Conversely if one side of an inscribed triangle is a diameter of the circle then the triangle is a right angle and the angle opposite the diameter is the right angle.
Theorem: A quadrilateral can be inscribed in a circle if and only if its opposite angles are supplementary.