Search Results for “Quadrilateral”

Cyclic Quadrilateral Theorem
The Cyclic Quadrilateral Theorem states that for a quadrilateral inscribed in a circle, the measures of opposite angles must add to 180 degrees. Drag the points and observe the angle measures to see how this theorem holds true.
Euclids Elements - Book 2 - Proposition 14
One of my favorite apps because it looks deceptively simple, but takes some really creative thinking. This app creates a square (in red) that has the same area as a given quadrilateral.