Hey, gafftaper, I forgot to tell you I thought of you the other day while watching

*The Colbert Report.* Steven was going off a rant that included "There are only four countries today that don't use the metric

system: US, [something] [something] and Alaska!"

I had forgotten about the Shop Math section in Backstage Handbook. I just looked for my copy and of course can't find it. I've bought at least 4 friggin' copies of that

book, but someone always "borrows" it or I give a copy to someone more needy than myself. I'm now going to order two copies. Again!

I'll admit that I had to look up for verification the

EFL formula. There it was on the first

page of

*Lighting the Stage, Art & Practise* by Willard F. Bellman, where I had written it in 1980. Also written was the f-stop formula, which I've never used.

And speaking of looking up formulas that are never used. There is a typo in

*Backstage Handbook* (brown

cover). Expressing the quadratic formula, there's only a "-" sign after the "2ab". It should be a "±" (plus and/or minus) before the radical. At the time, I believe I called for a global recall, but never received a corrected copy. If I remember right, it IS correct in the blue

cover edition.

A free white

china marker to the first respondent who can demonstrate a real-world purpose for the quadratic equation!

Call now, operators are standing by.

I swear it's a conspiracy by educators who make these things up just so they have something to teach and grade students. Unlike deriving a lighting

fixture's multiplication factor from its

beam angle using trigonometry: [Excel format] Multiplying Factor(MF) =2*TAN((x/2)*PI()/180), where x is the

beam angle in degrees. BTW, the "*PI()/180" is just to force Excel to

express the answer in degrees rather than radians, and therefore isn't needed if calculating by

hand.