There is no shape that has four sides and three corners. Two-dimensional shapes, known as polygons, have an equal number of sides and angles. In addition, none of the common three-dimensional shapes have four sides and three corners.
A polygon with three corners is a triangle, which also has three sides. Four-sided polygons are known as quadrilaterals. Examples of quadrilaterals include the square, rectangle and parallelogram. Common three-dimensional shapes include the cube, triangular prism, cone, cylinder and tetrahedron. None of the shapes have three corners, or vertices. Some, such as the cylinder, have no corners. Others, such as the tetrahedron, have four vertices.