Question 831675
If it's a 45 45 90 triangle, it has some special formulas for sides 
It is a right triangle but also isosceles triangle where you have two sides equal each other.
those two sides will be x, and then the hypotenuse will be {{{sqrt(2)x}}}
Now you have the hypotenuse which means you have {{{sqrt(2)x}}} = {{{12}}} 
{{{x}}} = {{{12/(sqrt(2))}}}
{{{x}}} = {{{6sqrt(2)}}}
TA-DAH
Your two other sides are {{{6sqrt(2)}}} :D