Determine the area of triangles given in the Determine the area of plane. given in the coordinate plane. Words to Know Write the letter of the definition next to the matching word as you work through the lesson. You may use the glossary to help you. area coordinate plane parallelogram right triangle A. a quadrilateral in which both pairs of opposite sides are parallel B. a triangle having an interior angle measuring 90 degrees C. the amount of space enclosed by a two- dimensional figure D. a system for locating points in two dimensions that uses a horizontal axis and a vertical axis