## Elementary Geometry for College Students (7th Edition) Clone

Since $AD = CD$ and $AB = BC$, the quadrilateral $ABCD$ is a kite.
We know that $\angle DAB = \angle DCB = 90^{\circ}$ $AD = CD$, because each line is a radius of the circle. We can use the Pythagorean theorem to show that the length of $AB$ is equal to the length of $BC$: $AB = \sqrt{(BD)^2-(AD)^2}$ $AB = \sqrt{(BD)^2-(CD)^2}$ $AB = BC$ Since $AD = CD$ and $AB = BC$, the quadrilateral $ABCD$ is a kite.