Question

if the radius of a circle is 21 cm . find it's area and circumference
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Answer 1

Answer:

area = 1386 cm^2

circumference = 132 cm

Step-by-step explanation:

radius = 21 cm

area of circle = pi x r^2

therefore area = 22/7 x 21 x 21 = 1386 cm^2

circumference = 2 x pi x r

= 2 x 22/7 x 21

= 132 cm

Answer 2

• The area of the circle is 1386 cm sq.
• The circumference of the circle is 132 cm

SOLUTION:

Given:

The radius (r) of a circle is 21 cm

To find:

The area of the circle and the circumference of the circle.

• The formula used  to find the area of a circle

= πr² units sq.  [In which 'r' is the 'radius' of the circle]

So,

The area of the circle is

= 22/7 * 21 * 21

= 22 * 3 * 21

= 1386 cm sq.

• The formula to find the circumfernce of the circle is

= 2πr units.  [In which 'r' is the 'radius' of the circle]

So,

The circumference of the circle is

= 2 * 22/7 * 21

= 44 * 3

= 132 cm