First use your calculator to find $\displaystyle{{\cos{{39}}}}^{\circ}={0.777145961}\usepackage{cmbright}\Huge\$ .

Then find the reciprocal of this: $\displaystyle{{\sec{{39}}}}^{\circ}=\frac{{1}}{{{\cos{{39}}}}^{\circ}}\text{}={1.286759566}\ldots\usepackage{cmbright}\Huge\$

Finally, round off to 1.287.