We have:
A = pi/4
b = c = 3
To finde the length a^2 we use the cosine law:
[tex]a^2=b^2+c^2-2bc\cdot\cos A[/tex]Replace the given values
[tex]\begin{gathered} a^2=3^2+3^2-2(3)(3)\cdot\cos \frac{\pi}{4} \\ a^2=9+9-18\cdot\frac{\sqrt[]{2}}{2} \\ a^2=18-9\sqrt[]{2} \\ a^2=9(2-\sqrt[]{2}) \\ a^2=3^2(2-\sqrt[]{2}) \end{gathered}[/tex]Answer: A.
