Answer
(a) impossible.
(b) possible.
(c) impossible.
Work Step by Step
(a) For any value of $\theta$ for which the secant function is defined,
$|\sec\theta|$ should be greater than or equal to 1. But $|-\frac{2}{3}|=\frac{2}{3}\lt1$. Therefore, the given statement is impossible.
(b) The tangent function can take on any real number value. Thus $\tan\theta=1.4$ is possible.
(c) The range of $\cos\theta$ is $[-1,1]$. As 5 is not included in this range, $\cos\theta=5$ is impossible.
