FORMULABANK

Area of an Equilateral Triangle

$0,433\cdot s^2=\mathrm{Area}$

$0,433\cdot 3^2=3,897$

Area of a Square

$s^2=\mathrm{Area}$

$3^2=9$

Area of a Regular Pentagon

$1,7205\cdot s^2=\mathrm{Area}$

$1,7205\cdot 3^2\approx 15,4845$

Area of a Regular Hexagon

$2,5981\cdot s^2=\mathrm{Area}$

$2,5981\cdot 3^2=23,38$

Area of a Regular Heptagon

$3,6339\cdot s^2=\mathrm{Area}$

$3,6339\cdot 3^2=32,71$

Area of a Regular Octagon

$4,8284\cdot s^2=\mathrm{Area}$
$4,8282\cdot 3^2=43,46$

Area of a Regular Nonagon

$6,1818\cdot s^2=\mathrm{Area}$
$6,1818\cdot 3^2=55,64$

Area of a Regular Polygon

n: number of sides
s: side length

$\mathrm{Sum\; of\; angles}=180\cdot (n-2)$

$\frac{1}{4}\cdot \tan \left(\frac{\mathrm{Sum\; of\; angles}}{2n}\right)\cdot s^2\cdot n=\mathrm{Area}$