we know that
The formula of the law of cosines is
[tex]z^{2}=a^{2} +b^{2}-2*a*b*cos (Z)[/tex]
in this problem we have
[tex]16^{2}=18^{2} +19^{2}-2*18*19*cos (Z)\\256=324+361-684*cos (Z)\\256=685-684*cos (Z)\\-429=-684*cos (Z)\\\\cos (Z)=\frac{429}{684}\\\\ \\Z=arc\ cos(\frac{429}{684})\\\\\\Z= 51.157[/tex]
Round to the nearest whole degree
Z=51 degrees
therefore
the answer is
51 degrees
