15 terms

Triangle

A 3-sided figure

Quadrilateral

A 4-sided figure

Pentagon

A 5-sided figure

Hexagon

A 6-sided figure

Heptagon

A 7-sided figure

Octagon

An 8-sided figure

Nonagon

A 9-sided figure

Decagon

A 10-sided figure

Trapezoid

A quadrilateral with one pair of parallel sides

Parallelogram

A quadrilateral with 2 pairs of parallel sides

Convex Polygon

A polygon in which all of the diagonals lie in the interior of the polygon.

Concave Polygon

A polygon in which any point of a diagonal lies in the exterior of the polygon.

Diagonal

A segment connecting any two nonconsecutive vertices of a polygon

Polygon

A plane figure formed by a finite number of segments.

Regular Polygon

A convex polygon that is both equilateral and equiangular