While checking out at my local Ace Hardware, I noticed a little book that is black and a little bigger than 3" x 5". It is called "POCKET REF" and is by Thomas J. Glover. It was $12.98.
In it, there are zillions of facts, information, knots, formulas, weights, welding, symbols, taps and dies, squares cubes and roots, rope, metallurgy, conversion charts, constants, and everything from A to Z. Well, from abrasives to wounds, abdominal.
I snatched one for personal references, and for when someone here asks a question, and I want to appear bigger and smarter than I am in person.
It has a trig section that covers the Pythagorean theorem question posed not long ago, along with working with triangles other than right triangles.
Absolutely tons of information for those of us whose minds are already so full we can't keep up with our own cell phone numbers. Or car keys.
If you see one, pause and take a look. There is another that deals with welding and metal, and I would like to find it, but I forget its name right now. A pocket size book. If you know the name, please post it.