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Grade 7 - Mathematics
9.4 Area of a Circle - II

Example:
The circumference of a circle is 30.8 cm. Find its area.

Solution:
If r is the radius of a circle, we have
Circumference (C) = 2pr
Therefore, the area of the circle = p r2
A = p(C/2p)2
A = C2 / 4p
Given that,
C = 30.8 cm.
A = (30.8)2/4 * 7/22
A = 6640.48 / 88
A = 75.46 sq cm.
Therefore, the area of he circle (A) = 75.46 sq cm.


Directions: Read the above example carefully and answer the following questions. Also write at least 10 examples of your own.

Q 1: The circumference of a circle is 44 cm. Find x if its area is given by 77x sq cm.
4 cm
2 cm
8 cm
None of these

Q 2: The circumference of a circle is 16x cm. Find x if its area is given by 6.16 sq cm.
None of these
0.55 cm
1.09 cm
1.23 cm

Q 3: The circumference of a circle is 22p cm. Find its area.
None of these
380.13 sq cm
38.01. sq cm
3.801 sq. cm

Q 4: The circumference of a circle is 33 cm. Find its area.
86.625 sq cm
8.6625 sq cm
866.25 sq cm
None of these

Q 5: The circumference of a circle is (550/5) cm. Find its area.
9.625 sq cm
None of these
962.5 sq cm
96.25 sq cm

Q 6: The circumference of a circle is 3.96 cm. Find x if its area is given by 0.4158x sq cm.
5 cm
None of these
3 cm
6 cm

Question 7: This question is available to subscribers only!

Question 8: This question is available to subscribers only!


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