Question

If a circle has a circumference of 12 cm, then what will the area be if the radius

is decreased by 2 cm?*
O
41 cm
O
361 cm
O
251 cm
O
161 cm
ооп cm?
If a circle has an area of 251 mm?, then what will the area be if the radius is
increased by 3mm?

Answer 1

A) The area of circle is 2.54 mm²

B) The area of circle is 1533.60 mm²

Explanation:

Given as :

A ) circumference of circle = 12 cm

∵ circumference of circle is
`2* \Pi * radius`

Or, 12 =
`2* \Pi * radius`

Or, Radius of circle =
`(12)/(2* 3.14)`

Or, Radius of circle =
`(6)/( 3.14)`

∴ Radius of circle = 1.91 cm

Now, The radius of circle is decrease by 2

So, New radius R = 1.91 - 2 = - 0.09 cm

∴ The area of circle =
`\Pi * radius^(2)`

Or, The area of circle = 3.14 × ( - 0.09 )²

C' = 0.0254 cm² = 2.54 mm²

B ) The area of circle = 251 mm²

The radius of circle is increase by 3 mm

So, R' = 1.91 cm + 3 mm

Or, R' = ( 1.91 × 10 ) mm + 3 mm

Or, R' = 22.1 mm

So, Area of new circle C'' =
`\Pi * radius^(2)`

Or, C'' =
`\Pi * (22.1)^(2)`

Or, C'' = 1533.60 mm²

Hence , A) The area of circle is 2.54 mm²

B) The area of circle is 1533.60 mm² Answer