Chiều dài hcn là:

8+15=23(cm)

Chu vi hcn là:

(8+23)x2=62(cm)

Diện tích hcn là:

8x23=184(cm²)

\(\dfrac{x-241}{17}+\dfrac{x-220}{19}+\dfrac{x-195}{21}+\dfrac{x-166}{23}=10\\ \Leftrightarrow\left(\dfrac{x-241}{17}-1\right)+\left(\dfrac{x-220}{19}-2\right)+\left(\dfrac{x-195}{21}-3\right)+\left(\dfrac{x-166}{23}-4\right)=0\\ \Leftrightarrow\dfrac{x-258}{17}+\dfrac{x-258}{19}+\dfrac{x-258}{21}+\dfrac{x-258}{23}=0\)

\(\Leftrightarrow\left(x-258\right)\left(\dfrac{1}{17}+\dfrac{1}{19}+\dfrac{1}{21}+\dfrac{1}{23}\right)=0\\ \Leftrightarrow x-258=0\left(vì.\dfrac{1}{17}+\dfrac{1}{19}+\dfrac{1}{21}+\dfrac{1}{23}\ne0\right)\\ \Leftrightarrow x=258\)

Diện tích hình tròn là:

(2:2)x(2:2)x3,14=3,14(m²)

Đáp số: 3,14m²