Question

If $\tan \theta =4$, where $\theta$ is an acute angle, find $\sec \theta$ using the identity.

Answer 1

$\tan \theta =4$ (Given)
$\therefore 1+{\tan }^2\theta ={\sec }^2\theta$
$1+4^2={\sec }^2\theta$
${\sec }^2\theta =17$
$\therefore \sec \theta =\sqrt{17}$