31. Find the volume of the solid generated when the shaded region is revolved about the given line.
Given:
Region: Ay
Q
y = 12 - x, y = 12, x = 144
Line of revolution: y = 12
To find the volume of the solid obtained by revolving the region about y = 12, we can use the method of cylindrical shells.
The height of each cylindrical shell is given by the difference between the upper and lower curves: (12 - x) - 12 = -x.
The radius of each cylindrical shell is the distance from the line of revolution (y = 12) to the curve y = 12 - x. This distance is given by the equation: 12 - (12 - x) = x.
The differential volume of each cylindrical shell is given by the formula: dV = 2πrh dx, where r is the radius and h is the height.
Therefore, the volume of the solid is given by the integral of the differential volume from x = 144 to x = 145:
V = ∫[144,145] 2πx(-x) dx
Now, we can solve the integral to find the volume of the solid.