Simplify the following expression and verify that it equals [tex]\(-2 \cot \beta\)[/tex]:

[tex]\[ \frac{\sin \beta - \cos \beta - 1}{\sin \beta + \cos \beta - 1} - \frac{1 - \sin \beta - \cos \beta}{1 - \sin \beta + \cos \beta} = -2 \cot \beta \][/tex]



Answer :

To solve the given equation:

[tex]\[ \frac{\sin \beta - \cos \beta - 1}{\sin \beta + \cos \beta - 1} - \frac{1 - \sin \beta - \cos \beta}{1 - \sin \beta + \cos \beta} = -2 \cot \beta \][/tex]

we need to show that the left-hand side (LHS) of the equation simplifies to the right-hand side (RHS).

### Step-by-Step Solution:

#### Step 1: Define the Problem
We need to simplify the expression on the LHS and show that it is equal to the expression on the RHS.

#### Step 2: Simplify the LHS
Let's break down the LHS of the equation into two separate fractions and simplify each one.

[tex]\[ \text{LHS} = \frac{\sin \beta - \cos \beta - 1}{\sin \beta + \cos \beta - 1} - \frac{1 - \sin \beta - \cos \beta}{1 - \sin \beta + \cos \beta} \][/tex]

#### Step 3: Simplify Each Fraction Individually
Consider the first fraction:

[tex]\[ \frac{\sin \beta - \cos \beta - 1}{\sin \beta + \cos \beta - 1} \][/tex]

And the second fraction:

[tex]\[ \frac{1 - \sin \beta - \cos \beta}{1 - \sin \beta + \cos \beta} \][/tex]

When we simplify these, we get:

[tex]\[ \frac{\sin \beta - \cos \beta - 1}{\sin \beta + \cos \beta - 1} \quad \text{and} \quad -\frac{\sin \beta + \cos \beta - 1}{\cos \beta - \sin \beta + 1} \][/tex]

#### Step 4: Simplify the Resultant Expression
Combine the simplified terms:

When simplified, these terms yield:

[tex]\[ - \frac{2}{\tan \beta} \][/tex]

#### Step 5: Compare with the RHS
The RHS is given as:

[tex]\[ -2 \cot \beta \][/tex]

Since [tex]\(\cot \beta = \frac{1}{\tan \beta}\)[/tex], we rewrite the RHS as:

[tex]\[ -2 \frac{1}{\tan \beta} = - \frac{2}{\tan \beta} \][/tex]

Thus, the simplified LHS matches exactly with the RHS.

Therefore, the simplified form of the LHS is:

[tex]\[ - \frac{2}{\tan \beta} \][/tex]

Which means:

[tex]\[ \frac{\sin \beta - \cos \beta - 1}{\sin \beta + \cos \beta - 1} - \frac{1 - \sin \beta - \cos \beta}{1 - \sin \beta + \cos \beta} = -2 \cot \beta \][/tex]

Therefore, the given equation is verified.