Hexagonul regulat se imparte in 6 triunghiuri echilaterale congruente, deci aria lui va fi 6·AΔechilateral.
[tex]A_{\triangle echilateral}= \frac{l^2 \sqrt{3} }{4}= \frac{100 \sqrt{3} }{4}=25 \sqrt{3} \\
A_{hexagon}=6*25 \sqrt{3}=\underline{150 \sqrt{3}~cm^2} [/tex]
