First of all, I want to clarify something about PI.
PI is an irrational number, that is, it can not be expressed with a finite number of digits or as a fraction of two numbers. PI cannot even be expressed as a repeating sequence of digits.
Secondly, unless you are in elementary school, PI^(1/2) is a totally legitimate answer/number to use and in fact it is much more accurate then 1.772. The same goes for the square root of 3 or e^(2/3)
Hope I was help full.