#### polygons [1]

Geometric plane figures with several sides and a number of equal angles.

#### trapezoid

Quadrilateral with two sides (bases) that are parallel. It is isosceles when it has two sides that are equal and not parallel, and rectangle when two of its sides form a right angle.

#### rectangle

Quadrilateral whose opposite sides are equal in length; the sides meet at right angles.

#### square

Equilateral rectangle with four right angles.

#### rhombus

Equilateral parallelogram.

#### triangle

Three-sided polygon; triangles are scalene (no side is equal to any other) isosceles (two sides equal) or equilateral (all sides equal).