Since the opposite angles are supplementary, an isosceles trapezium is a cyclic quadrilateral. Thus, ABCD is a rectangle as each internal angle is 90°. 8. If the non-parallel sides of a trapezium are equal, prove that it is cyclic.
i don't have time but to prove that an isosceles trapezium is always cyclic, you have to prove that if you add the opposite angles, you will get 180 degrees.
