Shapes (Area and Perimeter) Formulas and Notes

Circle

Area \displaystyle = \pi r^{2}

Perimeter \displaystyle = 2 \pi r

Square

Area \displaystyle = s^{2}

Perimeter \displaystyle = 4s

Rectangle

Area \displaystyle = lb

Perimeter \displaystyle = 2l + 2b

Kite

Area \displaystyle = \frac{1}{2}ab

Rhombus

Area \displaystyle = \frac{1}{2}ab

Trapezoid/Trapezium

Area \displaystyle = \frac{1}{2}h(b1+b2)

Parallelogram

Area \displaystyle = hb

Ellipse

Area \displaystyle = \pi ab

Annulus

Area \displaystyle = \pi R^{2} - \pi r^{2}