Student Tutorial: Quadrilateral Concepts: Definitions


Study these terms related to quadrilaterals. You can also turn on the screen reader and click on the image to have it read to you.

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Quadrilateral. A four-sided polygon, the sum of whose interior angles is 360°.

Rectangle. A parallelogram with four 90° interior angles.

Rhombus. A parallelogram with all four sides congruent.

Square. A parallelogram with four congruent sides and four interior 90° angles.

Trapezoid. A quadrilateral with one pair of parallel sides.

Kite. A quadrilateral with two pairs of congruent, adjacent sides.

Parallelogram. A quadrilateral whose opposite sides are congruent and parallel. Opposite angles are congruent. Adjacent angles are supplementary.

Interior Angles. of a Quadrilateral There are four angles that make up the interior angles of a quadrilateral. Their sum is 360°.

Congruent Quadrilaterals. Quadrilaterals that have the same size and shape. Corresponding angles and sides are congruent.

Area of a Rectangle. Since a rectangle has square corners, the area is the product of the length and width of the rectangle.

Area of a Parallelogram Since a diagonal divides a parallelogram into two congruent triangles, the area of the parallelogram is twice the triangle area.

Area of a Rhombus. Since rhombus diagonals are perpendicular bisectors, the area of the rhombus is the sum of the triangle areas--or one half the product of the diagonals.

Area of a Square. Since a rectangle has square corners and congruent sides, the area is the square of any side length.

Area of a Trapezoid. Since a diagonal divides a trapezoid into two triangles, the area of the trapezoid is the sum of the area of the triangles. The parallel sides mean the triangles have the same height