# Area and perimeters

## Circumference of a circle

$\displaystyle C = 2 \pi r$

## Area of a circle

$\displaystyle A = \pi r^2$

## Perimeter of a triangle

$\displaystyle P = a + b + c$

## Area of a triangle

$\displaystyle A = \frac{1}{2} bh$

• The area of an equilateral triangle is

$\displaystyle A = \frac{1}{4}s^2\sqrt{3}$

# Volume and surface area

## Volume of a cube

$\displaystyle v(x) = x^3$

## Surface area of a sphere

$\displaystyle A(r) = 4\pi r^2$

## Volume of a sphere

$\displaystyle v(r) = \frac{4}{3}\pi r^3$

where r is the radius of a sphere

## Volume of a cone

$\displaystyle v(r) = \frac{1}{3}\pi r^2 h$

where r is the radius of the base, and h is the height of a cone

## Volume of a cylinder

This only applies to a right cylinder.

$\displaystyle v(r) = {\pi}r^2h$

where r is the radius of the base, and h is the height of a cylinder