If the radius of a circle is doubled, by what factor does its area increase? यदि किसी वृत्त की त्रिज्या दोगुनी कर दी जाए, तो उसका क्षेत्रफल किस कारक से बढ़ जाएगा?
A
2 times (2 गुना)
B
4 times (4 गुना)
C
8 times (8 गुना)
D
$\pi$ times ($\pi$ गुना)
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Correct Answer 4 times
Explanation
Area = $\pi r^2$. If $r$ becomes $2r$, then Area = $\pi (2r)^2 = 4\pi r^2$. So, it increases by 4 times.