Question

Find the area of the region between two concentric circular paths. If the radii of the circular paths are 210 m. and 490 m. respectively.​

Answer 1

Given :

• The radii of the circular paths are 210 m. and 490 m.

To Find :

• The area of the region between two concentric circular paths.

Solution :

Area of the outer circle :

$\: \qquad \dashrightarrow \sf{{ \pi \: \times {(490)}^{2} {m}^{2}}}$

$\: \qquad \dashrightarrow \sf{{ \ \dfrac{22}{7} \times \:490 \times 490 \: {m}^{2}}}$

$\: \qquad \dashrightarrow \sf{{ \ \dfrac{22}{ \cancel{7}} \times \cancel{490} \times 490 \: {m}^{2}}}$

$\: \qquad \dashrightarrow \sf{{ \ {22} \times 70 \times 490 \: {m}^{2}}}$

$\: \qquad \dashrightarrow \bf{{ \ 754600 \: {m}^{2}}}$

⠀

Area of the inner circle :

$\: \qquad \dashrightarrow \sf{{ \pi \: \times {(210)}^{2} {m}^{2}}}$

$\: \qquad \dashrightarrow \sf{{ \ \dfrac{22}{7} \times \:210 \times 210 \: {m}^{2}}}$

$\: \qquad \dashrightarrow \sf{{ \ \dfrac{22}{ \cancel{7}} \times \cancel{210} \times 210 \: {m}^{2}}}$

$\: \qquad \dashrightarrow \sf{{ \ {22} \times 30 \times 210 \: {m}^{2}}}$

$\: \qquad \dashrightarrow \bf{{ \ 138600 \: {m}^{2}}}$

⠀

Therefore,

Area of the region inside the circular paths :

$\: \qquad \dashrightarrow \sf{{ \ (754600 - 138600 ) \: {m}^{2}}}$

$\: \qquad \dashrightarrow \bf{{ \ 616000 \: {m}^{2}}}$