Find the area of the region bounded by the curve y2 = 2x and x2 + y2 = 4x
y2 = 2x is a parabola
In y2 = 2x parabola it is not defined for negative values of x hence the parabola will be to the right of Y-axis passing through (0, 0)
x2 + y2 = 4x is equation of circle
The general equation of circle is given by x2 + y2 + 2gx + 2fy + c = 0
Centre of circle is (-g, -f) and radius is
In x2 + y2 – 4x = 0, 2g = -4 ⇒ g = -2 and f = c = 0
Hence center is (-(-2), 0) that is (2, 0) and radius is which is 2
Hence plot the circle and parabola roughly and to mark the intersection points solve the parabola equation and circle equation simultaneously
Put y2 = 2x in x2 + y2 = 4x
⇒ x2 + 2x = 4x
⇒ x2 – 2x = 0
⇒ x(x – 2) = 0
⇒ x = 0 and x = 2
Put x = 2 in y2 = 2x
⇒ y2 = 2(2)
⇒ y = ±2
Hence the circle and parabola intersects at (0, 0), (2, 2) and (2, -2)
By integrating we will get the area only in the 1st quadrant but given parabola and circle are symmetric about X-axis hence area above and below X-axis will be equal
Hence area of shaded region will be twice the area we will get by integration in 1st quadrant …(a)
Observe that
⇒ area of shaded in 1st quadrant = area under circle – area under parabola …(i)
Let us find area under circle
x2 + y2 = 4x
⇒ y2 = 4x – x2
Integrate from 0 to 2
Using
Now let us find area under parabola
⇒ y2 = 2x
⇒ y = √2√x
Integrate from 0 to 2
Using (i)
⇒ area of shaded in 1st quadrant = unit2
Using (a)
The area required of shaded region = unit2