kite

A kiteis a quadrilateral with reflection symmetry across a diagonal.

\documentclass[tikz,margin={4cm 0cm}]{standalone}
\usepackage{tkz-euclide}
%
\begin{document}
\begin{tikzpicture}
    \tkzDefPoint(0,0){A}
    \tkzDefPoint(2,2){B}
    \tkzDefPoint(6,0){C}
    \tkzDefPoint(2,-2){D}
    \tkzDrawPolygon[very thick](A,B,C,D)
	%
	\tkzDrawSegments[thick](A,C B,D)
	\tkzInterLL(A,C)(B,D) \tkzGetPoint{M}
	%
	\tkzMarkSegments[mark=|](A,B D,A)
	\tkzMarkSegments[mark=||](B,C C,D)
	\tkzMarkSegments[mark=|||](B,M M,D)
	%
	\tkzMarkRightAngle(C,M,D)
\end{tikzpicture}
\end{document}

Some authors restrict "kite" to exclusively convex quadrilaterals; in such a case, a non-convex kite is called a dart.