quotating not parallel walls

[com_che]

Sorry, I have a problem, I have to quote two walls not parallel at the beginning and at the end, but the instrument quota, giving it the surface option, then tells me that they are not parallel. . .
How can I do that?

Thank you very much

 

[MB78]

da revitoped http://www.youtube.com/watch?v=1rd5y52h1cc&feature=youtu.be
guarda a 2:35

bye
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