you spin me right round

Question 1

variable to integrate for volume of revolution

Answer 1

dx

Question 2

variable to integrate for surface of revolution

Answer 2

• ds (arc length)
• becomes sqrt(1 + (dy/dx)^2)dx

Question 3

how to calculate volume of revolution

Answer 3

• int pi * y^2 dx

Question 4

how to calculate surface of revolution

Answer 4

• int 2 * pi * y ds
• change ds to dx
• int 2 * pi * y * sqrt(1 + (dy/dx)^2) dx