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← JEE Main 2022 · 27 Jul · Shift 1
MathematicsSingle correct+4 / -1Question 9 of 90

JEE Main 2022 · 27 Jul · Shift 1, Mathematics question 9

The area of the smaller region enclosed by the curves y2=8x+4y^2=8x+4 and x2+y2+43x−4=0x^2+y^2+4\sqrt3x-4=0 is equal to

Choose one option
Answer and worked solution

Official answer: C

Curves. The circle has centre (−23,0)(-2\sqrt3,0) and radius 4. Solving with y2=8x+4y^2=8x+4 gives x2+(8+43)x=0x^2+(8+4\sqrt3)x=0, so they meet at x=0x=0, y=±2y=\pm2.

Smaller region (inside the circle, right of the parabola):
2∫02[(16−y2−23)−y2−48]dy.2\int_0^2\left[\left(\sqrt{16-y^2}-2\sqrt3\right)-\frac{y^2-4}8\right]dy.

Evaluate. ∫0216−y2 dy=23+4π3\int_0^2\sqrt{16-y^2}\,dy=2\sqrt3+\frac{4\pi}3, so the area is 2[4π3−23+23]=13(4−123+8π)2\left[\frac{4\pi}3-2\sqrt3+\frac23\right]=\frac13\left(4-12\sqrt3+8\pi\right).

(C)