# Surface area of a plane

1. Nov 25, 2011

### aftershock

SECOND EDIT: Never mind I think I figured it out. My problem was assuming the shape was a square. It was a rhombus. Thanks anyways guys

This isn't a homework problem, just something I was thinking of. Let's say I have the plane z= x+y and I wanna find the area of the region from 0≤x≤2 and 0≤y≤2

∫∫√[(1+(f$_{x}$)2 + (f$_{y}$)2] dA

(the f subscripts are partial derivatives)

Would give me an answer of 4√3

But just using geometry I think the portion of the plane would just be a square with sides of √8
giving me an answer of 8.

Where'd I go wrong?

EDIT: I realized this probably belongs in another section, but as far as I can tell I can't delete this thread, so please feel free to move it if its not appropriate here.

Last edited: Nov 25, 2011
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Can you offer guidance or do you also need help?
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