A8. Gašper drew a square, a circle, and an equilateral triangle on a piece of paper. The perimeter of each of these shapes is $7.2 \mathrm{~cm}$. In which case are these shapes arranged from the shape with the smallest area to the shape with the largest area?
(A) triangle, square, circle
(B) circle, square, triangle
(C) triangle, circle, square
(D) circle, triangle, square
(E) square, triangle, circle
A8. From the data for the perimeter $o=7.2 \mathrm{~cm}$, we calculate the side of the equilateral triangle $a_{tr}=\frac{7.2 \mathrm{~cm}}{3}=2.4 \mathrm{~cm}$, the side of the square $a_{kv}=\frac{7.2 \mathrm{~cm}}{4}=1.8 \mathrm{~cm}$, and the radius of the circle $r_{kr}=\frac{7.2 \mathrm{~cm}}{2 \pi}=1.15 \mathrm{~cm}$. The area of the equilateral triangle is $S_{tr}=\frac{a_{tr}^{2} \sqrt{3}}{4}=2.49 \mathrm{~cm}^{2}$, the area of the square is $S_{kv}=a_{kv}^{2}=3.24 \mathrm{~cm}^{2}$, and the area of the circle $S_{kr}=\pi r^{2}=4.15 \mathrm{~cm}^{2}$. The ranking of the areas from smallest to largest is: triangle, square, circle.

Note: There is a minor error in the original text. The side of the equilateral triangle should be calculated as $a_{tr}=\frac{7.2 \mathrm{~cm}}{3}=2.4 \mathrm{~cm}$, not $\frac{7.2 \mathrm{~cm}}{4}=1.8 \mathrm{~cm}$. However, the area calculation for the triangle is correct based on the value $a_{tr}=1.8 \mathrm{~cm}$.