In order to find the value for 'a', we can use the law of cosine, which is given by
[tex]a^2=b^2+c^2-2bc\cos A[/tex]
From the given triangle, we have
[tex]b=13,c=11,A=108^{\circ}[/tex]
On substituting these values in the above mentioned formula, we get
[tex]a^2=13^2+11^2-2\cdot 13 \cdot 11 \cos 108^{\circ}\\\\a^2=169+121-2\cdot 13 \cdot 11 \cos 108^{\circ}\\\\\\a^2=378.38\\\\a=19.45[/tex]
Thus, the length of a is 19.45
Second option is correct.
