Given that [tex]$\sec \theta = -\frac{37}{12}$[/tex], what is the value of [tex]$\cot \theta$[/tex] for [tex]$\frac{\pi}{2} \ \textless \ \theta \ \textless \ \pi$[/tex]?

A. [tex][tex]$-\frac{35}{12}$[/tex][/tex]
B. [tex]$-\frac{12}{35}$[/tex]
C. [tex]$\frac{12}{35}$[/tex]
D. [tex][tex]$\frac{35}{12}$[/tex][/tex]



Answer :

To solve this problem, we start with [tex]\(\sec \theta = -\frac{37}{12}\)[/tex] and aim to find [tex]\(\cot \theta\)[/tex] in the interval [tex]\(\frac{\pi}{2} < \theta < \pi\)[/tex].

1. Calculate [tex]\(\cos \theta\)[/tex]:

Since [tex]\(\sec \theta = \frac{1}{\cos \theta}\)[/tex], we can find [tex]\(\cos \theta\)[/tex] by taking the reciprocal of [tex]\(\sec \theta\)[/tex]. Therefore,
[tex]\[ \cos \theta = \frac{1}{\sec \theta} = \frac{1}{-\frac{37}{12}} = -\frac{12}{37}. \][/tex]

2. Determine [tex]\(\sin \theta\)[/tex]:

We need to find [tex]\(\sin \theta\)[/tex] using the Pythagorean identity: [tex]\(\sin^2 \theta + \cos^2 \theta = 1\)[/tex].

Plugging in our value for [tex]\(\cos \theta\)[/tex],
[tex]\[ \cos^2 \theta = \left(-\frac{12}{37}\right)^2 = \frac{144}{1369}. \][/tex]
Hence,
[tex]\[ \sin^2 \theta = 1 - \cos^2 \theta = 1 - \frac{144}{1369} = \frac{1369}{1369} - \frac{144}{1369} = \frac{1225}{1369}. \][/tex]

Since [tex]\(\theta\)[/tex] is in the second quadrant ([tex]\(\frac{\pi}{2} < \theta < \pi\)[/tex]), where sine is positive, we take the positive square root:
[tex]\[ \sin \theta = \sqrt{\frac{1225}{1369}} = \frac{35}{37}. \][/tex]

3. Calculate [tex]\(\cot \theta\)[/tex]:

We know that [tex]\(\cot \theta = \frac{\cos \theta}{\sin \theta}\)[/tex]. Using the values obtained,
[tex]\[ \cot \theta = \frac{\cos \theta}{\sin \theta} = \frac{-\frac{12}{37}}{\frac{35}{37}} = -\frac{12}{35}. \][/tex]

Therefore, the value of [tex]\(\cot \theta\)[/tex] is:
[tex]\[ -\frac{12}{35}. \][/tex]

The correct choice is [tex]\(\boxed{-\frac{12}{35}}\)[/tex].