Geometry formulas for area and perimeter of shapes

Nonagon

Nonagon
$$\textbf{Area of the nonagon}$$
$$A = \frac{1}{4} 9 b^2 \frac{\cos\big(\frac{\pi}{9}\big)}{\sin\big(\frac{\pi}{9}\big)} $$Calcular
$$\textbf{Perimeter of the nonagon}$$
$$P = 9 b $$Calcular