geometry formulas for area and perimeter of shapes

Heptagon

circle area and perimeter formula
$$\textbf{Area of the heptagon}$$
$$A = \frac{1}{4} 7 b^2 \cot\bigg(\frac{\pi}{7}\bigg) $$
$$ = \frac{1}{4} 7 b^2 \frac{\cos\big(\frac{\pi}{7}\big)}{\sin\big(\frac{\pi}{7}\big)} $$
$$\textbf{Perimeter of the heptagon}$$
$$P = 7 b $$