Question

what is the formula for area of an equilateral triangle and a decagon?

Answer 1

Dear Student,

$$\begin{gathered} AreaofEquilateralTriangle=\frac{\sqrt{3}}{4}\times {\left(side\right)}^2 \\ AreaofDecagon=\frac{5}{2}\times (side{)}^2\times \sqrt{5+2\sqrt{5}} \end{gathered}$$

Regards,