math question

Several people also came up with that figure (though none stated the process as concisely as you) but the real problem is that he only described it as a 6" circle. Diameter would be my guess, too, but there's no reason it couldn't be circumference, or even radius (probably not area, although that's another possibility.)

All the best, Stan

It's very hard to believe you ever flunked algebra. Algebra is particularly accessible to people with minds which can reduce information to orderly, understandable elements---like you just did. If you really had trouble with algebra, it must have been awhile back. If that soured you on the subject, maybe you should take another look at it on your own. About the amount of algebra you would get in two or three college quarters (short of the advanced algebra you need to ease into calculus) is actually quite useful in real world applications---and you can teach it to yourself surprisingly quickly with a good self-study text.

My semi-outsider's take on the major areas of high school math is that geometry is almost pure logic; it teaches you the value of careful linear thinking. Algebra is about the manipulation of values in equilibrium. It teaches a method of problem solving that really trancends math, IMHO. Trig is about the manipulation of simple mathematical relationships; it would be the most useful basic math for working people except that it's essentially useless without a calculator that costs about $10 (to distinguish it from the ones that are, for practical purposes, free), and, for me, it just rises above that threshold of things I can keep in my mind without using regularly. Calculus is the point at which you cross into a way of describing complicated situations purely in terms of math. It has enormous real world applications, but none for the casual user, because there are no casual users. That's my take, anyway.

All the best, Stan

Nobody understood Steve's question because he failed to specify how the 6" measurement related to the circle---radius, diameter, or circumference. Every answer was correct for whatever dimension was used. The answer for a circle with an AREA of 6 (square) inches hasn't been submitted yet.

Excuse the details, but it also could make a difference if you need the arc length around the circle or the straight line distance across part of the circle. At 1/10 degree, there is no measureable difference. But at 45 degrees there is 1/2 inch difference.

The radius (r) of your circle is 6/2=3 inches.
The length of the arc we will call "y" is .001 inches.

For very small angles, the length of the arc (for a radius of one) is close enough to the sine that we can use the sine instead.

angle = arcsine(y/r) = arcsine(.001/3) = arcsine(.00033)
angle = .019 degrees

So a tenth of a degree is about .005 inches.

Another solution, using geometry:

The circumference of the circle is pi*d, and there are 360 degrees in the circle. So the total circumference is 3.1415 * 6 = 18.85 inches. Since 360 degrees equals 18.85 inches, .001 inches is .001 inches * (360 degrees /18.85 inches) = .019 degrees. Same answer as before: Each tenth of a degree is about .005 inches.

My quick-calcs without double checking (wife waiting for me for supper)

Pi x d= circumference

circ= 18.8496"

360 degrees in a circle, so along the circumference you should have .0524 inches per degree and then .0052" per 1/10 of a degree. Hope thats what you were looking for. (Wasn't 100% sure of what you were asking.)

Find the sine of 1 degree. This is roughly .017" per inch. Multiply by 3 (radius of 6" dia). Divide by 10.