Question 44134
Use Pythagoras's theorem {{{a^2+b^2=c^2}}}
where "a" and "b" are the sides touching the right-angle.
{{{a=5sqrt(3)}}}
{{{b=3+3sqrt(3)}}}
{{{a^2+b^2=c^2}}}
{{{(5sqrt(3))^2+(3+3sqrt(3))^2=c^2}}}
{{{(25*3)+9+9sqrt(3)+9+9sqrt(3)+(9*3)=c^2}}}
{{{75+18+18sqrt(3)+27=c^2}}}
{{{75+18+18sqrt(3)+27=c^2}}}
{{{120+18sqrt(3)=c^2}}}
{{{c=sqrt(120+18sqrt(3))}}}

I hope this helps 
P.S. I am trying to start up my own homework help website. I would be extremely grateful if you would e-mail me some feedback on the help you received to adam.chapman@student.manchester.ac.uk