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(sin x)cosx

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Question

(sin x)cosx 

Sum
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Solution

Let y = (sin x)cosx 

⇒ log y = log(sin x)cosx = cosx log(sinx)

Differentiate both sides w.r.t. x, we get

⇒ `1/y * "dy"/"dx" = cos x * "d"/"dx" (log sin x) + log sin x "d"/"dx" (cos x)`

= `cos x * 1/sinx * "d"/"dx" (sin x) + log sin x * (- sin x)`

= `cot x * cos x - log (sin x) * sin x`

∴ `"dy"/"dx" = y[cot x cos x - sin x * log(sin x)]`

= (sin x)cosx [cot x cos x – sin x · log(sin x)]

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Chapter 5: Continuity And Differentiability - Exercise [Page 109]

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NCERT Exemplar Mathematics Exemplar [English] Class 12
Chapter 5 Continuity And Differentiability
Exercise | Q 34 | Page 109

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