Thread: Math Question About Cants & Roundwood

Thanks for the help with the math.
However, since dia. may be here nor there on a round log and measuring the circ. is more accurate, what is the equation for sq"., if only the circ. is known? To answer my own question would it be:
(circ" divided by pi)x DxD X .7854?
Thanks,
John

You're making it too hard on yourself.

Since circumference (C) is already pi*D, and D*D*pi/4 is the area

Then (C/pi)*(C/pi)*pi/4 = area

or simplify

C*C/4/pi = area

John, you really should be asking your buddy Doug about these math problems.

Here's a little something to chew on (and it only works for shapes which are perfectly circular).

For a given value circumference, divide it by Pi to find the diameter, divide that by 2 to find the radius, square that and multiply it by Pi to find the area.  On my HP48 I can create a simple program to do all that thus (it's "Reverse Polish" language):

  <<  PI  /  2  /  SQ  PI  *  >>

Then after assigning the program to a button, I can key in a value and press the button to find the area of a circle for which that initial value was the circumference.

Here are some results (circumference on left, area on right):

    1    0.07957747
  10    7.95774715
100    795.774715

   2    0.31830989
   4    1.27323954
   6    2.86478898
   8    5.09295818

(each of the above left-hand values, when putting each "0" behind them, moves the decimal point to the right two more places, exactly as for "1")



Glen