Quote:
Originally Posted by iCurtis
Your math is right, but a quarter inch is not a half inch.  ... |
Quote:
Originally Posted by lukevanoort
Indeed, a quarter inch is not a half inch, but the equation for the area of a circle is pi*radius^2, and drill bits are measured in terms of diameter. So, a half inch bit has a quarter inch radius, and thus the area of the hole is pi*.25^2.
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Most of us learn the pi-R-squared formula for circular area in high school.
Engineers prefer the formula Area = (pi/4) * diameter^2, because measurement of a circle's diameter is generally more accurate than measurement of its radius. The diameter measurement only requires finding two (diametrically) opposite points on the circle, while a radius measurement requires finding the circle's center.
The pi-R-squared formula always reminds me of the old joke about the college kid who comes back to the farm and is asked to say something smart. When he replies "pi-R-squared", his father the farmer says, "son, you're still as dumb as the day you left here. Everyone knows that pie are round -- cornbread are squared."
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