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Let y= (\sin x)^{2} then dy/dx equals

  • Option 1)

    (\cos x)^{2}

  • Option 2)

    2\sin x \cos x

  • Option 3)

    2\sin x

  • Option 4)

    none of these

 

Answers (1)

best_answer

As we have learned 

Chain Rule for differentiation (indirect) -

Let  y = f(x)  is not in standard form then 

\frac{dy}{dx}=\frac{dy}{du}\times \frac{du}{dx}

ex:\:\:y=sin(ax+b)

Let\:\;u=(ax+b)

then\:\:y=sin \:u

so\:\:\frac{dy}{du}=cos \:u\:\:and\:\:\frac{du}{dx}=a

\therefore \frac{dy}{dx}=\frac{dy}{du}\times \frac{du}{dx}=a\:cos \:u

=a\:cos(ax+b)

 

- wherein

Where\;\:y=f(u)\:\;and\;\;u=f(x)

 

 

\frac{dy}{dx}=\frac{dy}{dx}*\frac{du}{dx} , Let u= \sin x\Rightarrow \frac{du}{dx}=\cos x and also

 y=u^{2}\Rightarrow \frac{dy}{dx}=2u

\therefore \frac{dy}{dx} = 2u*\cos x= 2\sin x \cos x

 

 

 

 


Option 1)

(\cos x)^{2}

Option 2)

2\sin x \cos x

Option 3)

2\sin x

Option 4)

none of these

Posted by

Himanshu

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