Question 147089
Use the Pythagorean Theorem.  For a right triangle where the legs are {{{a}}} and {{{b}}}, and the hypotenuse is {{{c}}}, {{{c^2=a^2+b^2}}}, so {{{c=sqrt(a^2+b^2)}}}.


For your example:
{{{a=10}}} and {{{b=20}}}, {{{c=sqrt((10)^2+(20)^2)=sqrt(100+400)=sqrt(500)}}} roughly 22.36 feet or about 22 feet, 4 and 3/8 inches.  That ought to be close enough for log cabin building.


To do the decimal to feet/inches conversion, take the decimal part of the measurement and multiply times 12.  .36 X 12 = 4.328 roughly.  Now compare the decimal part of that result to the following table:


1/8 = .125
1/4 = .250
3/8 = .375
1/2 = .500
5/8 = .625
3/4 = .750
7/8 = .875


Pick the decimal value closest to the decimal part of your calculation and use the corresponding fractional value.  That gets you within 1/8 inch which should be close enough.  .328 corresponds most closely with .375, so 3/8 inch.  Putting it all back together:  22 feet, 4 and 3/8 inches.


Hope that helps