[SOLVED] determining a rectangle's aspect ratio
NOTE: I reposted this in Advanced Geometry before realizing there was a "Go Advanced" button here for doing that. I'll leave this open here for now but I think it's a more difficult problem than I first thought...
It's been too long since I've had to figure something like this out. I'm hoping someone will be kind enough to help. I'm attaching a picture of what I'm working on as it will make it easier to describe. (I'll leave the image up until someone's given me an answer).
I'm looking for the width (line dc) of this rectangle when the height (line de) is 5 inches (and for the formula needed to figure it out). Note that the blue line (da) and red line (ac) are equal in length and that angle abc is 90 degrees. Also note that line ec is a diagonal of the rectangle from the lower left corner to the upper right corner and line af runs from the middle of line dc to the lower right corner (f).
Just from experimenting a bit I know that line dc is about 7.1 inches. I'd like the formula for getting the exact length.
Thank you in advance. I didn't think this would be that hard to figure out but I don't really know how to even approach solving it.