Please explain in detail as much possible:
Find the volume of a triangle with sides y = 2, y = x+1, y = 11-x. The vertices are (5, 6), (1, 2) and (9, 2). Find the volume by rotating about y-axis:
(i) Method of disks
(ii) Cylindrical shell method
The solution applies two different methods to calculate the volume of solid of revolution formed when R is revolved about the y-axis.