Instead of using complicated 2D and 3D integrals, learn how to place an appropriate type of a directional multiplication table.
New way of "Directional Multiplication" used for 2D and 3D integration, where it can be easily concluded that
1.circumference of a circle is 2r, where 2 (r=1) is a length unit.
2.Area of a complete circle is: r(r+1)/2 (2x1)
3.Volume of a sphere is: r(r+1)(2r+1)/6 (2x1)^2
4.in 3D sin, (meter per cycle) and f (cycle per second) are independent.
5.Volume of a 3D sin is: (r(r+1)/2)( (+1)/2)(2/ x1 x1)