Originally Posted by

**DavidAP** Thanks, I think I tried that originally, but when those formulas are plugged into a spreadsheet, a circular reference is created and the formulas fail. How can we solve for D when we don't know E?

A little background: the original equation comes from the TV world, where DAR=PAR*(W/H). That's Display Aspect Ratio equals Pixel Aspect Ratio times (Width divided by Height). From that equation I came up with A/B=D/E*(F/G). From there I came up with D/E=(A/B)/(F/G).

A common value for DAR is 4/3, and common values for Width and Height are 720 and 480. From there it's easy to figure out that PAR=0.888889. What I need is to know are the two numbers that when the second is divided into the first (D/E) the quotient is 0.888889. From reading reference materials and trial and error with spreadsheet formulas, I know that if F/G=720/480 and A/B=4/3, then D/E=8/9, and if F/G=720x480 and A/B=16/9, then D/E=32/27, but I don't know how to arrive at those numbers on my own. For example, what's D if A/B=16/9 and F/G=720/352? What's E?

Thank you for your patience,

Dave