Answer:
b. [tex]x=\frac{5\pi}{6}[/tex]
Step-by-step explanation:
The given function is
[tex]\sec x=-\frac{2\sqrt{3} }{3},\:\:for\:\:\frac{\pi}{2}\le x \le \pi[/tex]
Recall that the reciprocal of the cosine ratio is the secant ratio.
This implies that;
[tex]\frac{1}{\cos x}=-\frac{2\sqrt{3} }{3}[/tex]
[tex]\Rightarrow \cos x=-\frac{3}{2\sqrt{3} }[/tex]
[tex]\Rightarrow \cos x=-\frac{\sqrt{3}}{2}[/tex]
We take the inverse cosine of both sides to obtain;
[tex]x=\cos^{-1}(-\frac{\sqrt{3}}{2})[/tex]
[tex]x=\frac{5\pi}{6}[/tex]
