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Question
If the radius of a circle is tripled, the area becomes ______.
Options
9 times
3 times
6 times
30 times
Solution
If the radius of a circle is tripled, the area becomes 9 times.
Explanation:
Let r be the radius of a circle.
∴ Area of circle = πr2
If radius is tripled, then new radius will be 3r.
∴ Area of new circle = π(3r)2 = 9π2 = 9 times of original
Hence, the area of a cirlce becomes 9 times to the original area.
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