If the small leg is 10, then the hypotenuse is 20, by the pattern of sides of a 30-60-90 triangle:
SHORT LEG = x,
LONG LEG = x sqrt(3)
HYP = 2X
If the long leg is 10 then the short leg is 10/sqrt(30) and the hyp is 20/sqrt(30).
Hope that helps! LMK if you have any more questions :-)