1. If [tex]\tan \theta = \frac{1}{\sqrt{5}}[/tex], what is the value of [tex]\frac{\operatorname{cosec}^2 \theta - \sec^2 \theta}{\operatorname{cosec}^2 \theta + \sec^2 \theta}[/tex]?



Answer :

Certainly! Let's solve the problem step-by-step.

### Step 1: Given Information and Initial Calculations

We are given that [tex]\(\tan \theta = \frac{1}{\sqrt{5}}\)[/tex].

### Step 2: Finding [tex]\(\sec^2 \theta\)[/tex]

We start by recalling the trigonometric identity:
[tex]\[ \sec^2 \theta = 1 + \tan^2 \theta \][/tex]

Since [tex]\(\tan \theta = \frac{1}{\sqrt{5}}\)[/tex], we find:
[tex]\[ \tan^2 \theta = \left(\frac{1}{\sqrt{5}}\right)^2 = \frac{1}{5} \][/tex]

Next, we compute [tex]\(\sec^2 \theta\)[/tex]:
[tex]\[ \sec^2 \theta = 1 + \frac{1}{5} = \frac{5}{5} + \frac{1}{5} = \frac{6}{5} = 1.2 \][/tex]

### Step 3: Finding [tex]\(\operatorname{cosec}^2 \theta\)[/tex]

We recall another trigonometric identity:
[tex]\[ \operatorname{cosec}^2 \theta = 1 + \cot^2 \theta \][/tex]

Using the fact that:
[tex]\[ \cot \theta = \frac{1}{\tan \theta} = \sqrt{5} \][/tex]

Then, we compute [tex]\(\cot^2 \theta\)[/tex]:
[tex]\[ \cot^2 \theta = (\sqrt{5})^2 = 5 \][/tex]

So, [tex]\(\operatorname{cosec}^2 \theta\)[/tex] is:
[tex]\[ \operatorname{cosec}^2 \theta = 1 + 5 = 6.0 \][/tex]

### Step 4: Calculating the Numerator and Denominator

We need to calculate the expression:
[tex]\[ \frac{\operatorname{cosec}^2 \theta - \sec^2 \theta}{\operatorname{cosec}^2 \theta + \sec^2 \theta} \][/tex]

First, find the numerator:
[tex]\[ \operatorname{cosec}^2 \theta - \sec^2 \theta = 6.0 - 1.2 = 4.8 \][/tex]

Next, find the denominator:
[tex]\[ \operatorname{cosec}^2 \theta + \sec^2 \theta = 6.0 + 1.2 = 7.2 \][/tex]

### Step 5: Finding the Final Expression

Finally, compute the value of the expression:
[tex]\[ \frac{\operatorname{cosec}^2 \theta - \sec^2 \theta}{\operatorname{cosec}^2 \theta + \sec^2 \theta} = \frac{4.8}{7.2} = \frac{2}{3} = 0.6666666666666666 \][/tex]

### Summary

The value of [tex]\(\frac{\operatorname{cosec}^2 \theta - \sec^2 \theta}{\operatorname{cosec}^2 \theta + \sec^2 \theta}\)[/tex] is approximately [tex]\(0.6666666666666666\)[/tex], or [tex]\(\frac{2}{3}\)[/tex].