The formula for calculating area of sector is:
[tex]\text{Area of Sector=}\frac{\theta\pi r^2}{360}[/tex][tex]\text{where }\theta=42^o\text{ , r=18 units and }\pi=\frac{22}{7}[/tex][tex]\text{Area of Sector= }\frac{42\times\frac{22}{7}\times18^2}{360}=\frac{6\times22\times324}{360}=118.8\approx118.80\text{ square units}[/tex]