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The area of the smaller region enclosed by the curves $$y^2 = 8x + 4$$ and $$x^2 + y^2 + 4\sqrt{3}x - 4 = 0$$ is equal to
Given curves are
$$y^2=8x+4$$
and
$$x^2+y^2+4\sqrt3\,x-4=0$$
First rewrite them.
Parabola:
$$y^2=8\left(x+\frac12\right)$$
Hence,
$$x=\frac{y^2-4}{8}$$
Circle:
$$x^2+4\sqrt3\,x+y^2-4=0$$
Completing the square,
$$x^2+4\sqrt3\,x+12+y^2=16$$
$$(x+2\sqrt3)^2+y^2=16$$
So the circle has centre
$$(-2\sqrt3,0)$$
and radius
$$4$$
Now find points of intersection.
Substitute
$$x=\frac{y^2-4}{8}$$
in the circle:
$$\left(\frac{y^2-4}{8}\right)^2+y^2+4\sqrt3\left(\frac{y^2-4}{8}\right)-4=0$$
Solving gives
$$y=\pm2$$
and corresponding
$$x=0$$
Hence, intersection points are
$$(0,2)\quad \text{and}\quad (0,-2)$$
Now the smaller enclosed region lies between:
- parabola on the right
- left arc of the circle on the left
For the circle,
$$x=-2\sqrt3+\sqrt{16-y^2}$$
Hence required area is
$$A=\int_{-2}^{2}\left[\frac{y^2-4}{8}-\left(-2\sqrt3+\sqrt{16-y^2}\right)\right]dy$$
Using symmetry,
$$A=2\int_0^2\left(\frac{y^2-4}{8}+2\sqrt3-\sqrt{16-y^2}\right)dy$$
Now,
$$\int_0^2\frac{y^2-4}{8}\,dy =\frac18\left[\frac{y^3}{3}-4y\right]_0^2 =-\frac23$$
Also,
$$\int_0^22\sqrt3\,dy=4\sqrt3$$
Now evaluate
$$\int_0^2\sqrt{16-y^2}\,dy$$
Using standard formula,
$$\int\sqrt{a^2-y^2}\,dy =\frac y2\sqrt{a^2-y^2}+\frac{a^2}{2}\sin^{-1}\frac ya$$
with
$$a=4,$$
$$\int_0^2\sqrt{16-y^2}\,dy =\left[\frac y2\sqrt{16-y^2}+8\sin^{-1}\frac y4\right]_0^2$$
$$=\sqrt{12}+8\cdot\frac{\pi}{6}$$
$$=2\sqrt3+\frac{4\pi}{3}$$
Therefore,
$$A=2\left(-\frac23+4\sqrt3-2\sqrt3-\frac{4\pi}{3}\right)$$
$$=2\left(2\sqrt3-\frac23-\frac{4\pi}{3}\right)$$
$$=4\sqrt3-\frac43-\frac{8\pi}{3}$$
Rearranging,
$$A=\frac{12\sqrt3-4-8\pi}{3}$$
Since area is positive,
$$A=\frac{8\pi+4-12\sqrt3}{3}$$
Hence, the required area is
$$\boxed{\frac13\left(4-12\sqrt3+8\pi\right)}$$.
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