A trapezoid in which non-parallel sides and base angles are equal.

regular trapezoid

• is a trapezoid whose non-parallel sides are congruent.

quadrilateral

• a figure formed by four straight lines that have six points of intersection.

rectangle

• a figure formed by four straight lines that have six points of intersection.

Rhombus. parallelogram with opposite equal acute angles, opposite equal obtuse angles, and four equal sides.

Square

Kite. A quadrilateral with two distinct pairs of equal adjacent sides.

Diagonal.
A straight line inside a shape that goes from one corner to another (but not an edge).

Parallelogram.
a four-sided plane rectilinear figure with opposite sides parallel.

Area.
The amount of space inside the boundary of a flat (2-dimensional) object such as a triangle or circle.

Polygon.
A plane shape (two-dimensional) with straight sides.

Radius.
a straight line from the center to the circumference of a circle or sphere.

Regular polygon.
If all angles are equal and all sides are equal, then it is a regular polygon (otherwise it is "irregular").

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