Question 463493
We know that the length of the side opposite 30 is half of the hypotenuse length,
thus this side is 13/2. To find the length of the side opposite 60 we use 

Pythagorean theorem: {{{13^2-(13/2)^2=x^2}}}=> {{{x^2= 169-169/4=3*169/4}}}=>

{{{x=sqrt(3*169/4)}}}=> {{{x=(13/2)sqrt(3)}}}.