Check all that apply. If [tex] \cos \theta=\frac{15}{17} [/tex], then:

A. [tex] \sec \theta=\frac{17}{15} [/tex]

B. [tex] \sin \theta=\frac{8}{17} [/tex]

C. [tex] \tan \theta=\frac{8}{15} [/tex]

D. [tex] \csc \theta=\frac{17}{8} [/tex]



Answer :

Okay, let's walk through solving the given question step-by-step.

We begin with the information provided:
[tex]\[ \cos \theta = \frac{15}{17} \][/tex]

### Step 1: Compute [tex]\(\sec \theta\)[/tex]
We know that [tex]\(\sec \theta\)[/tex] is the reciprocal of [tex]\(\cos \theta\)[/tex]:
[tex]\[ \sec \theta = \frac{1}{\cos \theta} = \frac{1}{\frac{15}{17}} = \frac{17}{15} \][/tex]
This matches option A, so A is correct.

### Step 2: Compute [tex]\(\sin \theta\)[/tex]
Next, we use the Pythagorean identity:
[tex]\[ \sin^2 \theta + \cos^2 \theta = 1 \][/tex]
Since [tex]\(\cos \theta = \frac{15}{17}\)[/tex], we have:
[tex]\[ \cos^2 \theta = \left(\frac{15}{17}\right)^2 = \frac{225}{289} \][/tex]
Thus,
[tex]\[ \sin^2 \theta = 1 - \cos^2 \theta = 1 - \frac{225}{289} = \frac{289}{289} - \frac{225}{289} = \frac{64}{289} \][/tex]
Taking the positive square root (since we're typically dealing with principal values unless otherwise specified):
[tex]\[ \sin \theta = \sqrt{\frac{64}{289}} = \frac{8}{17} \][/tex]
Option B states [tex]\( \sin \theta = \frac{15}{8} \)[/tex]. Since [tex]\(\frac{8}{17} \neq \frac{15}{8}\)[/tex], this option is incorrect.

### Step 3: Compute [tex]\(\tan \theta\)[/tex]
We know:
[tex]\[ \tan \theta = \frac{\sin \theta}{\cos \theta} = \frac{\frac{8}{17}}{\frac{15}{17}} = \frac{8}{15} \][/tex]
This matches option C, so C is correct.

### Step 4: Compute [tex]\(\csc \theta\)[/tex]
We know that [tex]\(\csc \theta\)[/tex] is the reciprocal of [tex]\(\sin \theta\)[/tex]:
[tex]\[ \csc \theta = \frac{1}{\sin \theta} = \frac{1}{\frac{8}{17}} = \frac{17}{8} \][/tex]
Option D states that [tex]\(\csc \theta = \frac{17}{15}\)[/tex]. Since [tex]\(\frac{17}{8} \neq \frac{17}{15}\)[/tex], this option is incorrect.

### Summary of Valid Choices:
A. [tex]\(\sec \theta = \frac{17}{15}\)[/tex] is correct.
B. [tex]\(\sin \theta = \frac{15}{8}\)[/tex] is incorrect.
C. [tex]\(\tan \theta = \frac{8}{15}\)[/tex] is correct.
D. [tex]\(\csc \theta = \frac{17}{15}\)[/tex] is incorrect.

Thus, the correct options are:
[tex]\[ \boxed{A \text{ and } C} \][/tex]