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The area of the smaller region of the circle x2+y2=8x^2 + y^2 = 8 cut off by the line x=2x = 2 is

Solution

✅ Correct Option: 1

The circle x2+y2=8x^2 + y^2 = 8 has center (0,0)(0, 0) and radius r=8=22r = \sqrt{8} = 2\sqrt{2}.


Substitute x=2x = 2 into the circle equation:

22+y2=82^2 + y^2 = 8

4+y2=84 + y^2 = 8

y2=4y^2 = 4

y=±2y = \pm 2

The line intersects the circle at (2,2)(2, 2) and (2,−2)(2, -2).


Since the circle's center is at the origin with radius 22≈2.832\sqrt{2} \approx 2.83, and the line is at x=2x = 2, the region where x>2x > 2 is the smaller region.


The smaller region is a circular segment with area = Sector area - Triangle area.

For the sector area, find the angle subtended by the chord at the center:

Point (2,2)(2, 2) makes angle θ1=tan⁡−1(2/2)=tan⁡−1(1)=π4\theta_1 = \tan^{-1}(2/2) = \tan^{-1}(1) = \frac{\pi}{4}

Point (2,−2)(2, -2) makes angle θ2=−π4\theta_2 = -\frac{\pi}{4}

Total angle: θ=π4−(−π4)=π2\theta = \frac{\pi}{4} - (-\frac{\pi}{4}) = \frac{\pi}{2}

Sector area =12r2θ= \frac{1}{2}r^2\theta

=12(8)(π2)= \frac{1}{2}(8)\left(\frac{\pi}{2}\right)

=2π= 2\pi


For the triangle with vertices (0,0)(0, 0), (2,2)(2, 2), (2,−2)(2, -2):

Base = distance from (2,2)(2, 2) to (2,−2)(2, -2) = 44 units

Height = perpendicular distance from origin to line x=2x = 2 = 22 units

Triangle area =12×4×2=4= \frac{1}{2} \times 4 \times 2 = 4


Area of smaller region = Sector area - Triangle area

=2π−4= 2\pi - 4

=2(π−2)= 2(\pi - 2)

Therefore, the area of the smaller region is 2(π−2)2(\pi - 2) square units.

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