# Octagon Calculator

Calculating a regular octagon (a polygon with eight vertices). This form is well known to us, as it is used on some road signs.

.**Octagon calculator, enter one known value**

**Side length (a)**

**Smaller diagonal (d1)**

**The middle diagonal (e)**

**Large diagonal (d3)**

**Perimeter (p)**

**Square (S)**

**The radius of the circumscribed circle (R)**

**Radius of the inscribed circle (r)**

## Formulas:

d = a * √*4 + 2 * √2*

e = a * ( 1 + √2 )

f = a * √*2 + √2*

Height = e = 2 * r

Р = 8 * а

S = 2 * a2 * ( 1 + √2 )

R = a / 2 * √*4 + 2 * √2*

r = a / 2 * ( 1 + √2 )

Angle: 135°, 20 diagonals.