Question

If the radius of a circle is 21 cm, then the area of the circle is _____ *​

Answer 1

Answer :-

• The area of the circle is 1386 cm²

Given :-

• The radius of a circle is 21 cm.

To find :-

• It's area.

Step-by-step explanation :-

• Here, the radius of a circle has been given to us. We have to find it's area.

We know that :-

$\underline{\boxed{\sf Area \: of \: a \: circle = \pi r^2}}$

Where,

• π = pi.
• r = Radius.

Here,

• pi = 22/7.
• Radius = 21 cm.

Substituting the given values in this formula,

$\rm Area = \dfrac{22}{7} \times 21 \times 21$

Reducing the numbers,

$\rm Area = \dfrac{22}{1} \times 3 \times 21$

Now let's multiply the remaining numbers since we can't reduce them anymore.

$\rm Area = 22 \times 3 \times 21$

Multiplying the numbers,

$\overline{\boxed{\rm Area = {1386\: cm}^{2}}}$

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Know more :-

What is a circle?

• A circle is a round figure which has no vertices, edges or faces. It consists of radii, chords, a diameter and a circumference. Infinite lines can be drawn inside a circle.

• Circumference of a circle = 2πr.

Where,

• r = Radius.

What is π?

• The ratio of circumference to diameter is denoted by π (read as pi) and it's approximate value is 22/7 or 3.14.

Answer 2

Answer:

Answer of this question is 1386 cm²

Step-by-step explanation:

Area of circle = πr²

= 22/7 x 21 x 21

= 22 x 63

= 1386 cm²