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Area of the region bounded by the curve y=sin⁡xy = \sin x and x-axis between x=π2x = \frac{\pi}{2} and x=3π2x = \frac{3\pi}{2} is

Solution

✅ Correct Option: 4

The area between the curve y=sin⁡xy = \sin x and the x-axis from x=π2x = \frac{\pi}{2} to x=3π2x = \frac{3\pi}{2} needs to be calculated. Area is always positive, even if the curve goes below the x-axis.


The behavior of sin⁡x\sin x in the given interval:

At x=π2x = \frac{\pi}{2}: sin⁡(π2)=1\sin\left(\frac{\pi}{2}\right) = 1

At x=πx = \pi: sin⁡(π)=0\sin(\pi) = 0

At x=3π2x = \frac{3\pi}{2}: sin⁡(3π2)=−1\sin\left(\frac{3\pi}{2}\right) = -1

From π2\frac{\pi}{2} to π\pi, the curve is above the x-axis (positive).

From π\pi to 3π2\frac{3\pi}{2}, the curve is below the x-axis (negative).


Since the curve crosses the x-axis at x=πx = \pi, the area must be calculated in two parts:

Total Area =Area1(π2 to π)+Area2(π to 3π2)= \text{Area}_1 \left(\frac{\pi}{2} \text{ to } \pi\right) + \text{Area}_2 \left(\pi \text{ to } \frac{3\pi}{2}\right)


For Area1_1 (above x-axis):

Area1=∫π/2πsin⁡x dx\text{Area}_1 = \int_{\pi/2}^{\pi} \sin x \, dx

=[−cos⁡x]π/2π= [-\cos x]_{\pi/2}^{\pi}

=[−cos⁡π]−[−cos⁡(π/2)]= [-\cos \pi] - [-\cos(\pi/2)]

=[−(−1)]−[0]= [-(-1)] - [0]

=1= 1


For Area2_2 (below x-axis):

Area2=∫π3π/2sin⁡x dx\text{Area}_2 = \int_{\pi}^{3\pi/2} \sin x \, dx

=[−cos⁡x]π3π/2= [-\cos x]_{\pi}^{3\pi/2}

=[−cos⁡(3π/2)]−[−cos⁡π]= [-\cos(3\pi/2)] - [-\cos \pi]

=[0]−[1]= [0] - [1]

=−1= -1

Since the curve is below the x-axis, taking absolute value: ∣−1∣=1|-1| = 1


Total Area =1+1= 1 + 1

=2= 2

Therefore, the area of the region is 22 square units.

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