List of formulas in elementary geometry

This is a short list of some common mathematical shapes and figures and the formulas that describe them.

Two-dimensional shapes

Shape Area Perimeter/Circumference
Square (where $s$  is the length of a side) $A=s^{2}$  $P=4s$
Rectangle ( $l$  is length, $w$  is width) $A=lw$  $P=2l+2w$
Circle (where $r$  is the radius and $d$  is the diameter) $A=\pi r^{2}$  $C=2\pi r$  or $C=\pi d$
Ellipse (where $a$  is the semimajor axis and $b$  is the semiminor axis) $A=\pi ab$
Triangle ($b$  is base; $h$  is height; $a,b,c$  are sides) $A={\frac {bh}{2}}$  $P=a+b+c$
Parallelogram ($b$  is base, $h$  is height, $a$  is side) $A=bh$  $P=2a+2b$
Trapezoid (where $a$  and $b$  are the bases) $A={\frac {a+b}{2}}h$
Sources:



Three-dimensional shapes

Shape Volume Surface area
Cube (where $s$  is the length of a side) $V=s^{3}$  $6s^{2}$
Rectangular Prism ($l$  = length, $h$  = height, $w$  = width) $V=lwh$  $S=2lw+2lh+2wh$
Sphere (where $r$  is the radius) $V={\frac {4\pi r^{3}}{3}}$  $S=4\pi r^{2}$
Right circular cylinder (where $r$  is the radius and $h$  is the height) $V=\pi r^{2}h$  $S=2\pi rh+2\pi r^{2}$
Sources: