It is a quadrilateral but I do not know which one it is:
It is a type of kite (Also known as a deltoid). On the left hand side of the image below is a convex kite, and on the right hand side is a concave kite.
Image by Wikipedia:
A concave kite is sometimes referred as a dart or arrowhead.
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It is a type of kite (Also known as a deltoid). On the left hand side of the image below is a convex kite, and on the right hand side is a concave kite.
Image by Wikipedia:
A concave kite is sometimes referred as a dart or arrowhead.