You can use cosine law to find c first.
\(c^2 = 8^2 + 11^2 - 2\cdot 8 \cdot 11 \cos 37^\circ\\ c \approx 6.666344593\)
Then, use cosine law again to find cos A.
\(8^2 = c^2 + 11^2 - 2\cdot c \cdot 11 \cos A\)
Substitute the value of c calculated above. Can you take it from here?