Question 1208866
Pythagorean Theorem, in three dimensions.  
The pen extends between two opposite corners.  You already have values for two of them and you
want to solve for the unknown dimension's value.


{{{d^2+2^2+12^2=13^2}}}

{{{d^2=169-4-144}}}

{{{d^2=169-148}}}

{{{d=sqrt(11)}}}

{{{d=3.32}}}