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How would I expand this?

  • Thread starter A9876
  • Start date
  • #1
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Homework Statement



r1 = √(L2+(y-0.5d)2)
r2 = √(L2+(y+0.5d)2)
Show that in the limit that both y and d are <<L r2 - r1 = yd/L

Homework Equations





The Attempt at a Solution



r2 - r1 =(√(L2+(y+0.5d)2)) - (√(L2+(y-0.5d)2))

Nevermind, I've figured it out but can't seem to be able to delete this post :s
 
Last edited:

Answers and Replies

  • #2
Simon Bridge
Science Advisor
Homework Helper
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I'd have tried substituting x=[(y-0.5d)/L]2 and used the binomial approximation.
Oh you figured it out - rather than delete the post - how about posting your result: that way others who get stuck can benefit.
 

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