Given [tex]\sin \theta = \frac{9}{41}[/tex], find [tex]\tan \theta[/tex].

A. [tex]\frac{40}{9}[/tex]
B. [tex]\frac{41}{9}[/tex]
C. [tex]\frac{9}{40}[/tex]
D. [tex]\frac{40}{41}[/tex]



Answer :

To solve for [tex]\(\tan \theta\)[/tex] given that [tex]\(\sin \theta = \frac{9}{41}\)[/tex], we should follow these steps.

### Step 1: Understand Trigonometric Identities
We will use the basic trigonometric identities - specifically the Pythagorean identity and the definition of tangent:
1. [tex]\(\sin^2 \theta + \cos^2 \theta = 1\)[/tex]
2. [tex]\(\tan \theta = \frac{\sin \theta}{\cos \theta}\)[/tex]

### Step 2: Use the Pythagorean Identity
Given [tex]\(\sin \theta = \frac{9}{41}\)[/tex], we first find [tex]\(\cos \theta\)[/tex]:
[tex]\[ \sin^2 \theta + \cos^2 \theta = 1 \][/tex]
Substitute [tex]\(\sin \theta\)[/tex] into this identity:
[tex]\[ \left(\frac{9}{41}\right)^2 + \cos^2 \theta = 1 \][/tex]
Calculate [tex]\(\sin^2 \theta\)[/tex]:
[tex]\[ \left(\frac{9}{41}\right)^2 = \frac{81}{1681} \][/tex]
Now solve for [tex]\(\cos^2 \theta\)[/tex]:
[tex]\[ \frac{81}{1681} + \cos^2 \theta = 1 \][/tex]
[tex]\[ \cos^2 \theta = 1 - \frac{81}{1681} \][/tex]
[tex]\[ \cos^2 \theta = \frac{1681}{1681} - \frac{81}{1681} \][/tex]
[tex]\[ \cos^2 \theta = \frac{1600}{1681} \][/tex]

### Step 3: Find [tex]\(\cos \theta\)[/tex]
[tex]\[ \cos \theta = \sqrt{\frac{1600}{1681}} \][/tex]
Since [tex]\(\theta\)[/tex] is typically taken within a range where cosine is positive:
[tex]\[ \cos \theta = \frac{\sqrt{1600}}{\sqrt{1681}} \][/tex]
[tex]\[ \cos \theta = \frac{40}{41} \][/tex]

### Step 4: Use the Definition of Tangent
Now, we know both [tex]\(\sin \theta\)[/tex] and [tex]\(\cos \theta\)[/tex]:
[tex]\[ \sin \theta = \frac{9}{41} \][/tex]
[tex]\[ \cos \theta = \frac{40}{41} \][/tex]

We can find [tex]\(\tan \theta\)[/tex] using its definition:
[tex]\[ \tan \theta = \frac{\sin \theta}{\cos \theta} \][/tex]
Substitute the known values:
[tex]\[ \tan \theta = \frac{\frac{9}{41}}{\frac{40}{41}} \][/tex]
Simplify the fraction division:
[tex]\[ \tan \theta = \frac{9}{40} \][/tex]

### Conclusion
The correct answer is:
[tex]\[ \tan \theta = \frac{9}{40} \][/tex]

Thus, the answer is:
[tex]\[ \boxed{\frac{9}{40}} \][/tex]

This matches choice C in the given options.