Which part of the problem are you having trouble with? Skeeter already told you how to solve part 1. Can you see that in the triangle the angle between the two known lengths is $\displaystyle \begin{align*} 105^{\circ} \end{align*}$? Do you know how to apply the cosine rule $\displaystyle \begin{align*} c^2 = a^2 + b^2 - 2\,a\,b\,\cos{(C)} \end{align*}$ to find an unknown length?