English

If Y = ( 2 − 3 Cos X Sin X ) , Find D Y D X a T X = π 4

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Question

\[\text{ If } y = \left( \frac{2 - 3 \cos x}{\sin x} \right), \text{ find } \frac{dy}{dx} at x = \frac{\pi}{4}\]

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Solution

\[\frac{dy}{dx} = \frac{d}{dx}\left( \frac{2 - 3 \cos x}{\sin x} \right)\]
\[ = \frac{d}{dx}\left( \frac{2}{\sin x} \right) - \frac{d}{dx}\left( \frac{3 \cos x}{\sin x} \right)\]
\[ = 2\frac{d}{dx}\left( \cos ec x \right) - 3\frac{d}{dx}\left( \cot x \right)\]
\[ = - 2 \cos ec x \cot x + 3 \cos e c^2 x\]
\[\frac{dy}{dx} at x=\frac{\pi}{4}= - 2 \cos ec \frac{\pi}{4} \cot \frac{\pi}{4} + 3 \cos e c^2 \frac{\pi}{4}\]
\[ = - 2\left( \sqrt{2} \right)\left( 1 \right) + 3 \left( \sqrt{2} \right)^2 \]
\[ = - 2\sqrt{2} + 6\]
\[ = 6 - 2\sqrt{2}\]
\[\]

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Chapter 30: Derivatives - Exercise 30.3 [Page 34]

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R.D. Sharma Mathematics [English] Class 11
Chapter 30 Derivatives
Exercise 30.3 | Q 20 | Page 34

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