Area Formulas for Polygons

Area of a parallelogram

A = bh Area = (base)(height)

Area of a rectangle

A = bh Area = (base)(height)

Area of a square

A = s^2 A = (side length)^2

Ratio of Areas (of similar polygons)

a^2:b^2 where a and b are scale factors

Area of a Circular Sector

Area = (x/360)(pi)(r^2) Area = (arc degree measurement / 360)(pi)(radius)^2

Area of a regular polygon

A = (1/2)ans OR A = (1/2)ap A = (1/2)(apothem)(number of sides)(side length) A = (1/2)(apothem)(perimeter)

Area of a triangle

A = (1/2)bh Area = (1/2)(base)(height)

Area of a rhombus

A = (1/2)d1d2 OR A = bh Area = (1/2)(diagonal 1)(diagonal 2) Area = (base)(height)

Area of a Trapezoid

A = (1/2)h(b1+b2) A = (1/2)(height)(base 1 + base 2)

Area of a circle

A = (pi)r^2 A = (pi)(radius)^2

Circumference of a circle

C = 2(pi)(r) OR C = (pi)d C = 2(pi)(radius) C= (pi)(diameter)

Length of an arc

Length = (x/360)(2)(pi)(r) OR (x/360)(pi)(diameter) Length = (arc degree measurement/360)(2)(pi)(radius)

Ratio of Perimeters (of similar polygons)

a:b where a and b are scale factors