The area of the region bounded by the curve $y=\sin x$ between $x=-\pi$ and $x=\frac{3 \pi}{2}$ is

The area of the region bounded by the curve $y=\sin x$ between $x=-\pi$ and $x=\frac{3 \pi}{2}$ is
  1. 2 (unit) $^{2}$
  2. 5 (unit) $^{2}$
  3. 3 (unit) $^{2}$
  4. 1 (unit) $^{2}$

Solution

Required area is shaded : $\begin{aligned} A &=2 \int_{0}^{\pi} \sin x d x+\int_{\pi}^{3 \pi / 2} \sin x d x \\ &=2\left[-\left.\cos x\right|_{0} ^{\pi}+[-\cos x]_{\pi}^{\frac{3 \pi}{2}}\right. \end{aligned}$ $=|2[-\cos \pi+\cos 0]|+\left[-\cos \left(\frac{3 \pi}{2}\right)+\cos \pi\right]$ $=2[-(-1)+1]+[0+(-1)]$ $=2(2)-(1)=5(\text { unit })^{2}$

Asked in: MHT CET 2020 (19 Oct Shift 2)

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