Polygons and Quadrilaterals

Diagonal

A segment that joins two nonconsecutive vertices of a polygon.

Interior angle

An angle formed by two sides of a polygon inside the polygon.

exterior angle

An angle formed by extending one side of a polygon.

Sum of Interior angles of a convex polygon

(n-2)180

Sum of Exterior angles of a convex polygon

360

the sue of one interior and one exterior angle of a polygon

180

the measure of one interior angle of a regular polygon

(n-2)180/n

The measure of each exterior angle of a regular polygon

360/n

The sum of interior angles for a pentagon

540

The sum of interior angles for an octagon

1080

Each exterior angle of a nonagon

40

Each exterior angle of a dodecagon

30

parallelogram

Quadrilateral with both pairs of opposite sides parallel

rectangle

equiangular quadrilateral

rhombus

Equilateral Quadrilateral

square

Regular Quadrilateral

rectangle property

congruent diagonals

rhombus property

perpendicular diagonals

rhombus property

Diagonals bisect angles they extend from

parallelogram property

both pairs of opposite sides congruent.

Parallelogram Property

Diagonals bisect one another

Parallelogram Property

Both pairs of opposite angles are congruent

Trapezoid

Quadrilateral with exactly one pair of opposite sides parallel