How to work out a Hip or Valley length (Part 2)

Alright so in the last post we went through the reasons why the multiplying factor is not the same for a Hip or Valley as it is for the roof or for that matter a section of barge, this time you get what you were after, the actual formula.
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To view the formula, or to save and edit this file go to: https://spreadsheets.google.com/ccc?key=0Am6p57KakXPVdFVLR3BGUGNqbnVQMGgxVjU0U1Vjdmc&hl=en select “File” -> “Download as” -> and then select “Excel” or “Openoffice”. If you have any issues just let me know in the comments.