TS EAMCET · Maths · Application of Derivatives
If the semi vertical angle of a cone is \(45^{\circ}\) and its height is \(20.025 \mathrm{~cm}\), then the approximate value of its curved surface area (in sq. \(\mathrm{cm}\) ) is
- A \(401 \pi \sqrt{2}\)
- B \(\frac{401 \sqrt{2}}{\pi}\)
- C \(401 \pi \sqrt{3}\)
- D \((401.2) \pi\)
Answer & Solution
Correct Answer
(A) \(401 \pi \sqrt{2}\)
Step-by-step Solution
Detailed explanation
Let \(r\) be the radius, \(h\) be the slant height and \(l\) be the slant height of a cone of semi vertical angle \(45^{\circ}\), then, \(r=h\) and \(l=\sqrt{2} h\) Let \(h=20\) and \(h+\Delta h=20.025 \Rightarrow \Delta h=0.025\) Let \(S\) be surface area, then…
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