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The area bounded by the curves y=cosx and y=sinx between the ordinates x=0\; and \; x=\frac{3\pi }{2}\; is 

  • Option 1)

    4\sqrt{2}-2

  • Option 2)

    4\sqrt{2}+2

  • Option 3)

    4\sqrt{2}-1

  • Option 4)

    4\sqrt{2}+1

 

Answers (1)

As we learnt in 

Area along x axis -

Let y_{1}= f_{1}(x)\, and \, y_{2}= f_{2}(x) be two curve then area bounded between the curves and the lines

x = a and x = b is

\left | \int_{a}^{b} \Delta y\, dx\right |= \left | \int_{a}^{b}\left ( y_{2}-y_{1} \right ) dx\right |

 

- wherein

Where \Delta y= f_{2}\left ( x \right )-f_{1}(x)

 Area=\int_{0}^{\frac{\pi }{4}}(\cos x-\sin x)dx+\int_{\frac{\pi }{4}}^{\frac{5\pi }{4}}(\sin x-\cos x)dx\\+\int_{\frac{5\pi }{4}}^{\frac{3\pi }{2}}(\cos x-\sin x)dx

=\left [ \sin x+\cos x \right ]_{0}^{\frac{\pi }{4}}+\left [ -\cos -\sin x \right ]_{\frac{\pi }{4}}^{\frac{5\pi }{4}}+\left [ \sin x+\cos x \right ]_{\frac{5\pi }{4}}^{\frac{3\pi }{2}}

=\sqrt{2}^{-1}+\left [ \sqrt{2} +\sqrt{2}\right ]+1(-1)+\sqrt{2}

=4\sqrt{2}-2

 


Option 1)

4\sqrt{2}-2

This option is correct 

Option 2)

4\sqrt{2}+2

This option is incorrect 

Option 3)

4\sqrt{2}-1

This option is incorrect 

Option 4)

4\sqrt{2}+1

This option is incorrect 

Posted by

Vakul

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