Surface Area of Revolution about x axis

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SUMMARY

The discussion focuses on calculating the surface area of revolution about the x-axis for the equation x² + (y - 2)² = 1. The user successfully derived the functions y = √(1 - x²) + 2 and y = 2 - √(1 - x²) but encountered difficulties with integration limits, specifically when y = 0, leading to complex calculations. The formula used for surface area is ∫ 2π * (√(1 - x²) + 2)√(1 + x²/(1 - x²))dx, which requires careful consideration of the curve's graph to determine appropriate limits.

PREREQUISITES
  • Understanding of calculus, specifically integration techniques.
  • Familiarity with the concept of surface area of revolution.
  • Knowledge of parametric equations and their graphical representations.
  • Experience with functions and their transformations in Cartesian coordinates.
NEXT STEPS
  • Study the method for calculating surface area of revolution using the disk and washer methods.
  • Learn how to determine integration limits based on the behavior of functions.
  • Explore graphing tools to visualize curves and their transformations.
  • Review advanced integration techniques, particularly those involving square roots and trigonometric identities.
USEFUL FOR

Students in calculus courses, mathematics educators, and anyone interested in advanced integration techniques and geometric applications in calculus.

mikbear
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Homework Statement


x^2 + (y - 2)^2 = 1
The hint given by the question was to split the function into 2

Homework Equations


Surface Area about x axis

The Attempt at a Solution


So i did this.
(y - 2)^2 = 1 - x^2
y = √(1 - x^2) +2 and y = 2 - √(1 - x^2)

The range I calculated
when y= 0; x = - √(-3) and x = √(-3)

I use the formula ∫ 2∏ * (√(1-x^2) + 2)√(1 + x^2/(1 - x^2))dx

Then i got stuck as it became messy
 
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mikbear said:
when y= 0; x = - √(-3) and x = √(-3)
That just means that y=0 does not happen. Your integration limits are determined by something else...
I use the formula ∫ 2∏ * (√(1-x^2) + 2)√(1 + x^2/(1 - x^2))dx
How did you get that formula?
 
mikbear said:

Homework Statement


x^2 + (y - 2)^2 = 1
The hint given by the question was to split the function into 2


Homework Equations


Surface Area about x axis


The Attempt at a Solution


So i did this.
(y - 2)^2 = 1 - x^2
y = √(1 - x^2) +2 and y = 2 - √(1 - x^2)

The range I calculated
when y= 0; x = - √(-3) and x = √(-3)

I use the formula ∫ 2∏ * (√(1-x^2) + 2)√(1 + x^2/(1 - x^2))dx

Then i got stuck as it became messy

The first step would be to identify the curve that is being rotated. Have you drawn its graph? Do you see why you would want to use the hint?
 

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