Answer
$\sec{2.8440}\approx -1.0460$
Work Step by Step
RECALL:
$\sec{\theta} = \dfrac{1}{\cos{\theta}}$
Use a calculator in radian mode and round-off the answer to four decimal places to obtain:
$\sec{2.8440}=\dfrac{1}{\cos{2.8440}} \approx -1.0460$