# Inscribed Quadrilateral Theorem

- Author:
- Sean Foster

There are two different Circles, Circle A and Circle C. Circle A has a quadrilateral that is inscribed in the circle. Circle C has a quadrilateral but it is not inscribed in the circle.
Follow the following directions then answer the questions at the bottom.
1. For Circle A. Move points E, F, G and H around. When you do this please notice how the angle measures change. Particularly, look at consecutive angles and at opposite angles in the quadrilateral.
2. For Circle C. Move points I, J, K and L around. KEEP POINT I OUTSIDE THE CIRCLE. When you do this notice how the angle measures change. Particularly, look at consecutive angles and at opposite angles in the quadrilateral.
Answer the questions below.

1. For both circles what did you notice about consecutive angles measures? Specifically their sums.
2. For Circle A, what did you notice about the opposite angles in the inscribed quadrilateral? Specifically their sums.
3. For Circle C, what did you notice about the opposite angles in the non-inscribed quadrilateral? Specifically their sums.
4. If a quadrilateral is inscribed in a circle what can you say about its opposite angles?