What Is a Convex Quadrilateral?

The four vertices, or corners, of a convex quadrilateral point outward and away from the interior of the shape. Two common types of convex quadrilaterals are squares and rectangles. The area of an irregular quadrilateral can be determined by finding the area of the four triangles made by the intersecting diagonals. All regular quadrilaterals, which have the same angle for each vertex, are convex.