Question

Find the area of a circular ring whose external and internal radii are 21cm amd 14 cm respectively.

Answer 1

Hey mate!

Here is your answer > >

External radii, R=21 cm

Internal radii, r=14 cm

Area of circular ring=$\pi$(R^2-r^2)

=> Area of circular ring=22/7 (21^2-14^2)

=22/7×245

=770 cm^2

Hope it helps!

Thankyou ☆ ☆

Answer 2

Area of ring is 770 cm².

Given:

• A circular ring.
• having external and internal radii are 21cm amd 14 cm respectively.

To find:

• Find the area of ring.

Solution:

Formula to be used:

Area of ring:$\bf \pi( {R}^{2} - {r}^{2} )$

Here; R is external radius and r is internal.

Step 1:

Write the given values.

As it is given that

External radius (R)=21 cm

Internal radius (r)=14 cm

Step 2:

Find area of ring.

Put the values in the formula.

$\text{Area of ring} = \frac{22}{7} ( {(21)}^{2} - ( {14)}^{2} )$

or

$= \frac{22}{7} (441 - 196)$

or

$= \frac{22}{7} \times 245$

or

$= 22 \times 35$

or

$\text{Area of ring} = 770 \: {cm}^{2}$

Thus,

Area of ring is 770 cm².

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