Using integration, find the area of the region in the first quadrant, enclosed by the x-axis, the line y=x and the circle x2+y2=32
Given the boundaries of the area to be found are,
• the circle, x2 + y2 = 32 ---(1)
• the line, y = x---- (2)
• Area should be in first quadrant.
From the equation, of the first circle, x2 + y2 = 32
• the vertex at (0,0) i.e. the origin
• the radius is 4√2 unit.
Now to find the point of intersection of (1) and (2), substitute y = x in (1)
x2 + x2 = 32
2x2 = 32
x2 = 16
x = ± 4
Substituting x in (2), we get y = ± 4
So the two points, A and B where (1) and (2) meet are A = (4,4) and B = (-4,-4)
As x and y have even powers for both the circles, they will be symmetrical about the x-axis and y-axis.
Consider the circle, x2 + y2 = 32, can be re-written as
----- (3)
Let us drop a perpendicular from A on to x-axis. The base of the perpendicular is C = (4, 0)
Now, the area to be found will be the area is
Area of the required region = Area of OADO.
Area of OADO= Area of OAC•+ Area of CADC
Area of OADOis
[Using the formula, and ]
[sin-1(1) = 90° and ]
= 4π
Area of the required region is 4π sq. units.