Convex and Concave Quadrilaterals Convex quadrilateral: A quadrilateral is called a convex quadrilateral, if the line segment joining any two vertices of the quadrilateral is in the same region. In figure, ABCD is a convex quadrilateral because AB, BC, CD, DA, AC, BD are in the same region of the quadrilateral. In a convex quadrilateral each angle measures less than … [Read more...] about Convex and Concave Quadrilaterals