Definition of Terms, ContinuedQuadrilateralsQuadrilaterals are plane figures bound by four straight sides. Four-sidedfigures with parallel opposing sides are further classified as parallelograms.A parallelogram having four equal sides and equal angles is called a square.A rhombus has four equal sides and equal opposing angles. A figure withequal opposing sides and equal angles is a rectangle. A figure with equalopposing sides and equal opposing angles is a rhomboid. Quadrilaterals withonly two parallel sides and no angles equal are trapezoids. If no sides and noangles are equal or parallel, the figure is called a trapezium. Trapezoids andtrapeziums are quadrilaterals but are not parallelograms.Figure 2-5 shows the six different types of quadrilaterals.Figure 2-5.—Quadrilaterals.Continued on next page2-7