Question

The diameter of a circle is 28 cm. Find its
(i) circumference (ii) area.
​

Answer 1

Step-by-step explanation:

I) The formula for the circumference of a circle is 2πr or πd, since 2×r=d.

So we will replace the diameter in the formula with the value of the diameter.

= π×28

= 22/7× 28 ( Note that we have taken the π to be 22/7 because 28 can be divided by 7. So we can easily cut the values)

=22/1×4 ( Because when we divide 28 by 7 we get 4, and when we divide 7 by 7 we get 1)

=22×4

=88cm

ii) The formula for area of a circle is πr^2.

So we need to find the radius for the formula.

r=d/2

r=28/2

r=14cm

Now we will replace the radius in the formula with its value.

= 22/7×14×14

=22/1×2×14( When we divide 14 by 7 we get 2, and when we divide 7 by 7 we get 1)

= 616sq cm

Hope this was any help.

Answer 2

Given:

• The diameter of a circle is 28 cm

To Find:

• (i) circumference (ii) area.

Solution:

Using Formulas:-

Diameter of circle:-

• d = 2r

Here,

• d is diameter
• r is radius

Circumference of circle:-

• 2πr

Here,

• π is 22/7
• r is radius

Area of circle:-

• A = πr²

Here,

• A is area
• π is 22/7
• r is radius

Putting the values in diameter formula,

=> 2r = 28

=> r = 28/2

=> r = 14 cm

Putting the values in circumference formula,

=> C = 2 × 22/7 × 14

=> C = 44/7 × 14

=> C = 44 × 2

=> C = 88cm

Finding out the area,

=> A = 22/7 × (14)²

=> A = 22/7 × 14 × 14

=> A = 22 × 2 × 14

=> A = 44 × 14

=> A = 616cm²

Henceforth, circumference is 88cm and area is 616cm²

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