Question

The radius of a circle is 10 cm.By how much is its radius is increased by 1 cm.( Take ♫ =3.14).​

Answer 1

Correct Question:

The radius of a circle is 10 cm. By how much is its circumference changed, if radius is increased by 1 cm. ( Take π = 3.14)

Given:

✰ The radius of a circle = 10 cm

✰ Radius is increased by 1 cm

✰ π = 3.14

To find:

✠ By how much is its circumference changed, if radius is increased by 1 cm.

Solution:

Let's understand the concept first! First we will find the circumference of circle by using formula, as we are already provided with the radius. Therefore, by putting the values in the formula and then doing the required calculations. After that, we will increase radius by 1 cm i.e, we will add 1 cm to the radius, which is already given to us. Afterwards, we will calculate the circumference with the increased radius, then we will subtract circumference of the radius from circumference with increased radius to get the change in circumference or how much circumference of circle changed.

Let's find out...

• The radius of a circle = 10 cm

✭ Circumference of circle = 2πr ✭

➛ Circumference of circle = 2 × 3.14 × 10

➛ Circumference of circle = 6.28 × 10

➛ Circumference of circle = 62.8 cm

When radius of a circle is increased by 1 cm

• Radius of a circle = 10 cm
• Radius of a circle = 10 + 1
• Radius of a circle = 11

➛ Circumference of circle with increased radius = 2 × 3.14 × 11

➛ Circumference of circle with increased radius = 6.28 × 11

➛ Circumference of circle with increased radius = 69.08 cm

Now,

➤ Change in circumference = Circumference of circle with increased radius - Circumference of circle

➤ Change in circumference = 69.08 - 62.8

➤ Change in circumference = 6.28 cm

∴ Its circumference will be changed by 6.28 cm, if radius is increased by 1 cm.

_______________________________

Answer 2

Correct Question :

The radius of a circle is 10 cm. By how much is its circumference changed, if radius is increased by 1 cm. Take π = 3.14

Given :

The radius of a circle is 10 cm. Radius is increased by 1 cm. Take π = 3.14.

To find :

By how much is its circumference changed, if radius is increased by 1 cm.

Solution :

We know that,

Circumference of circle = 2πr

= 2 × 3.14 × 10

= 62.8 cm²___( i )

Radius is increased by 1 cm

10 + 1 = 11 cm

Taking Radius as 11 cm

Circumference of circle = 2πr

= 2 × 3.14 × 11

= 69.08 cm²___( ii )

Subtracting ( i ) from ( ii )

69.08 - 62.8

= 6.28 cm²

Therefore,

Circumference is increased by 6.28 cm²