Answer
$-1.2992$
Work Step by Step
Step 1: Converting $140^{\circ}20'$ into decimal degrees:
$140^{\circ}20'=140(\frac{20}{60})^{\circ}=140.33^{\circ}$.
Step 2: Ensure that the calculator is in degrees.
Step 3: $\sec(140.33^{\circ})=\frac{1}{\cos (140.33^{\circ})}$
Step 4: Type $\frac{1}{\cos (140.33^{\circ})}$ into the calculator and press enter.
Step 5: Rounding out the answer to 4 decimal places, we get
$\frac{1}{\cos (140.33^{\circ})}\approx-1.2992$.
