Centre of Gravity of Plane Area:

Suppose a plane area enclosed by a curve y = ƒ(x), two ordinates x = a, x = b, and x-axis. Let P(x, y) be any arbitrary point on the curve. We take a strip at P of height y and thickness Δx. The area of this strip is y Δx and its C.G. is at (x,y/2). Therefore the co-ordinates of the C.G. of that plane area are

The co-ordinates of the C.G. of the area enclosed by a curve x = ƒ(y), y-axis and the lines y = c, y = d are shown as