\[S_1 = 3 \text{ см} \cdot 3 \text{ см} = 9 \text{ см}^2\]
\[S_2 = 2 \text{ см} \cdot 3 \text{ см} = 6 \text{ см}^2\]
\[S_3 = 8 \text{ см} \cdot 3 \text{ см} = 24 \text{ см}^2\]
\[S = S_1 + S_2 + S_3 = 9 \text{ см}^2 + 6 \text{ см}^2 + 24 \text{ см}^2 = 39 \text{ см}^2\]
Ответ: 39 см²