A1. The area of a regular hexagon is $96 \sqrt{3} \mathrm{~cm}^{2}$. What is the perimeter of this hexagon?
(A) $48 \mathrm{~cm}$
(B) $24 \mathrm{~cm}$
(C) $96 \mathrm{~cm}$
(D) $16 \mathrm{~cm}$
(E) $20 \mathrm{~cm}$
A1. We use the formula for the area of a regular hexagon $\frac{6 a^{2} \sqrt{3}}{4}=96 \sqrt{3}$ and calculate $a=8 \mathrm{~cm}$. The perimeter of a regular hexagon is $6 a=48 \mathrm{~cm}$.