Question

How do you evaluate $sec120°$?

Answer 1

Calculate the value of $sec120°$

$$\begin{gathered} sec120°=sec(1\times 90°+30°) \\ sec120°=-\cos ec30°\left[\because sec(90+\theta )=-\cos ec\theta \right] \\ sec120°=-\frac{1}{\sin 30°} \\ sec120°=-2 \end{gathered}$$

Hence, the value of $sec120°$ is $-2$