Question

if the diameter of circle is decreased by 10% then area will be decreased by​

Answer 1

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Given :

Radius of the circle is decreased by 10%.

Formula Used :

Area = A = π ( r )²

Calculation :

Let, radius initially,

r = 10 cm

⇒ Area,

A = π ( r )²

= 100 π cm²

⇒ New radius after 10% decrease,

r' = 10 × 90/100

= 9 cm

⇒ New area,

A' = π ( 9 )²

= 81 π cm²

∴ % decrease in area,

= 100 π - 81 π / 100 π

= 19 %

______________________________

Answer 2

Answer:

Step-by-step explanation:

Given :

Radius of the circle is decreased by 10%.

Area = A = π ( r )²

Let, radius initially,

r = 10 cm

⇒ Area,

A = π ( r )²

= 100 π cm²

⇒ New radius after 10% decrease,

r' = 10 × 90/100

= 9 cm

⇒ New area,

A' = π ( 9 )²

= 81 π cm²

∴ % decrease in area,

= 100 π - 81 π / 100 π

= 19 %