alleryएक वृत्ताकार वलय (रिंग) 21 cm और 14 cm त्रिज्या वाले वृत्तों से घिरा है। इसका क्षेत्रफल ज्ञात कीजिए (π = 22/7)।
A1078 cm²
B770 cm²
C308 cm²
D462 cm²
Answer & Solution
Correct answer: B. 770 cm²
वलय का क्षेत्रफल = π (21² - 14²) = (22/7)(245) = 770 वर्ग सेमी (cm²)।
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