Area of a circle | Questions and Answers | Formula

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The area of a circle is an area which is covered by circle in a plane. This can be measure by area of circle formula πr2.

Area of a Circle

The area of the circle is πr2 .
Where r is a radius of the circle and value of π = (22/7).

Question 1:
If radius of a circle is 7 cm. Find area of the circle.

Answer 1:
We have given, Radius = 7 cm and we know that π = (22/7)
Area of circle = πr2 cm2
= [22/7× (7)2 ]cm2
= [22/7×7×7] cm2
= 154 cm2
Hence area of the circle is 154 cm2

Question 2:
If radius of a circle is 3.5 m. Find area of the circle.

Answer 2:
We have given, Radius = 3.5 m and we know that π = (22/7)
Area of circle = πr2
= 22/7×(3.5)2
= [22/7 × 3.5 × 3.5] m2
= [22 × 0.5 × 3.5] m2
= 38.5 m2
Hence area of the circle is 154 m2

Question 3:
If diameter of a circle is 28 cm. Find area of the circle.

Answer 3:
We have given diameter (d) = 28 cm
Therefore radius = 28/2 cm = 14 cm
Area of circle = πr2
= 22/7×(14)2
= [22/7×14×14] cm2
= [22×2×14] cm2
= 616 cm2
Hence area of the circle is 616 cm2

Question 4:
If circumference of the circle is 220 cm. Find area of the circle.

Answer 4:
We have given circumference of circle (2πr) = 220 cm
We know that, (2πr) = 220 cm
2× 22/7 ×r = 220
44 r =220 ×7
r = (220 × 7)/ 44
r = 35 cm

Area of circle = πr2
= 22/7×(35)2
= [22/7×35×35] cm2
= [22×5×35] cm2
= 3850 cm2
Hence area of the circle is 3850 cm2.

Question 5:
A circle with diameter 14 cm. Find area of the circle.

Answer 5:
We have given diameter (d) = 14 cm
Therefore radius = 14/2 cm = 7 cm
Area of circle = πr2
= 22/7×(7)2
= [22/7×7×7] cm2
= [22×1×7] cm2
= 154 cm2
Hence area of the circle is 154 cm2.

Question 6:
If circumference of the circle is 22 cm. Find area of the circle.

Answer 6:
We have given circumference of circle (2πr) = 22 cm
We know that, (2πr) = 22 cm
2× 22/7 ×r = 22
44 r =22 ×7
r = (22 × 7)/ 44
r = 3.5 cm

Area of circle = πr2
= 22/7×(3.5)2
= [22/7×3.5×3.5] cm2
= [22×0.5×3.5] cm2
= 38.5 cm2
Hence area of the circle is 38.5 cm2

We can convert from meter to another smaller units, from given chart

1 kilo meter = 1000 meter
1 hecto meter = 100 meter
1 deca meter = 10 meter
1 deci meter = 1/10 meter
1 centi meter = 1/100 meter
1 mili meter = 1/1000 meter
1 meter = 100 cm
1 cm = 100 mm