Quadrilateral is any geometric figure with four straight sides. Some of the examples are square, rectangle, trapezoid, parallelogram, rhombus and so on. It is categorized into two types as convex and concave. If both segments lie inside the quadrilateral, then it is called as convex. If one of the segments lies outside the quadrilateral, then it is called as concave. You can findarea using the Area of Quadrilateral Formula on a 2D Line.