Shapes

Circle



$$area = πr^2$$
$$circumference = 2πr$$

Square



$$area = s^2$$
$$Perimeter = 4s$$

Rectangle



$$area = lb$$
$$Perimeter = 2l+2b$$

Kite



$$area = {1}/{2}ab$$

Rhombus



$$area = {1}/{2}ab$$

Trapezoid/Trapezium



$$area = {1}/{2}h(b1+b2)$$

Parallelogram



$$area = hb$$

Ellipse



$$area = πab$$

Annulus



$$area = πR^2-πr^2$$