Question
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2.
3.
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Answer (Detailed Solution Below)
Option 3 : $2300.57$ cm²
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Detailed Solution
सही उत्तर $2300.57$ cm² है।
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prepsnap.in • Part -AQuestion:
A hollow hemispherical metal bowl has an external radius of $14$ cm and a uniform thickness of $2$ cm. What is its total surface area? / एक खोखले अर्धगोलाकार धातु के कटोरे की बाहरी त्रिज्या $14$ सेमी और एकसमान मोटाई $2$ सेमी है। इसका कुल पृष्ठीय क्षेत्रफल क्या है?
1.
$2150.86$ cm²
2.
$2401.14$ cm²
3.
$2300.57$ cm²
4.
$2212.32$ cm²
Correct Answer: $2300.57$ cm²
Inner radius $r = 14-2 = 12$ cm. Total surface area $= 2\pi R^{2} + 2\pi r^{2} + \pi(R^{2}-r^{2}) = \pi(3R^{2}+r^{2}) = \pi(3\cdot196+144) = 732\pi = \frac{22}{7}\times732 = 2300.57$ cm². / आंतरिक त्रिज्या $r = 12$ सेमी; कुल क्षेत्रफल $= \pi(3R^{2}+r^{2}) = 2300.57$ सेमी²। The trap option (b) comes from using only $2\pi(R^{2}+r^{2})$ and forgetting the rim annulus $\pi(R^{2}-r^{2})$.
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