# How would I expand this?

## 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

## 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

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