Non right angled triangle

Answer:
18.06
Step-by-step explanation:
law of cos()
b^2 = (16.5)^2 + (17.1)^2 - 2(16.5)(17.1)cos(65)
[tex]\frac{3\sqrt{2}\sqrt{-3135\cos \left(65^{\circ \:}\right)+3137}}{10}\quad \begin{pmatrix}\mathrm{Decimal:}&18.06035\dots \end{pmatrix}[/tex]