Surface area of Revolution

  • Thread starter Jbreezy
  • Start date
  • #1
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Homework Statement


I want the surface area of Revolution about x from [-2,2] of y = |x|
So I want to know if I can take it x from [0,2] and just multiply this result by 2?

Homework Equations





The Attempt at a Solution



Set up
dy/dx = (5/(2√x))

S = 2 ∏ ∫ 5x^1/2(√ 1 +((5/(2√x))^2)

from x = 0 , to x = 2. Then multiply this result by 2? Is this OK to do?
 

Answers and Replies

  • #2
Dick
Science Advisor
Homework Helper
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Homework Statement


I want the surface area of Revolution about x from [-2,2] of y = |x|
So I want to know if I can take it x from [0,2] and just multiply this result by 2?

Homework Equations





The Attempt at a Solution



Set up
dy/dx = (5/(2√x))

S = 2 ∏ ∫ 5x^1/2(√ 1 +((5/(2√x))^2)

from x = 0 , to x = 2. Then multiply this result by 2? Is this OK to do?

Yes, the function y=|x| is symmetric around the y-axis, so you can double the result from [0,2]. But why do you think dy/dx = (5/(2√x))??
 
  • #3
582
0
Because I;m tired lol and looked off the wrong sheet. My bad. I had this problem done I just didn't know if I could do what I said I didn't see why not though. Thanks,
Later
 

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