Areas Related to Circles
NCERT Exemplar
CBSE
Grade 10
Question:
If the radius of a circle is doubled, its area becomes:
(a) 2 times
(b) 4 times
(c) 8 times
(d) 16 times
Step-by-Step Solution
Key Concept: Area $A = \pi r^2$. New area $A' = \pi (2r)^2 = 4 \pi r^2 = 4 A$.
$A' = \pi (2r)^2 = 4 \pi r^2 = 4A$. [1.0 Mark]
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🎯 Official CBSE Marking Scheme:
Evaluating area ratio $= 4$: 1.0 Mark
Correct Answer: 4 times
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