AB}}=\frac{-4+
1
}{-2+4}=\frac{-
3
}{2},\,\,\,{{S}_{
AD
}}=\frac{3+1}{2+4}=\frac{2}{3}\] \[{{S}_{AB}}\,.\,{{S}_{AD}}=-1.\]
HENCE
it is a rectangle.