Given the expression:

[tex]\[ \frac{(1+\cos \beta)+(1-\cos \beta)^2}{\sin ^2 \beta}=2\left(1+2 \cot ^2 \beta\right) \][/tex]

Simplify or prove the identity.



Answer :

Sure, let us verify the given equation step-by-step:

[tex]\[ \frac{(1+\cos \beta)+(1-\cos \beta)^2}{\sin^2 \beta} = 2\left(1+2 \cot^2 \beta\right) \][/tex]

### Step-by-Step Solution:

1. Simplify the Left-Hand Side (LHS):
[tex]\[ \frac{(1+\cos \beta)+(1-\cos \beta)^2}{\sin^2 \beta} \][/tex]

Start with simplifying the numerator:
[tex]\[ (1+\cos \beta) + (1 - \cos \beta)^2 \][/tex]

Expand [tex]\((1 - \cos \beta)^2\)[/tex]:
[tex]\[ (1 - \cos \beta)^2 = 1 - 2\cos \beta + \cos^2 \beta \][/tex]

Therefore, the numerator becomes:
[tex]\[ (1 + \cos \beta) + 1 - 2\cos \beta + \cos^2 \beta \][/tex]

Combine like terms:
[tex]\[ 1 + \cos \beta + 1 - 2\cos \beta + \cos^2 \beta = \cos^2 \beta - \cos \beta + 2 \][/tex]

Now, let's write the entire fraction:
[tex]\[ \frac{\cos^2 \beta - \cos \beta + 2}{\sin^2 \beta} \][/tex]

2. Simplify the Right-Hand Side (RHS):
[tex]\[ 2 \left(1 + 2 \cot^2 \beta\right) \][/tex]

Recall that:
[tex]\[ \cot \beta = \frac{\cos \beta}{\sin \beta} \][/tex]

Therefore:
[tex]\[ \cot^2 \beta = \left(\frac{\cos \beta}{\sin \beta}\right)^2 = \frac{\cos^2 \beta}{\sin^2 \beta} \][/tex]

Substitute [tex]\(\cot^2 \beta\)[/tex] back into the equation:
[tex]\[ 2 \left(1 + 2 \frac{\cos^2 \beta}{\sin^2 \beta}\right) \][/tex]

Distribute the 2:
[tex]\[ 2 + 4 \frac{\cos^2 \beta}{\sin^2 \beta} = 2 + 4 \cot^2 \beta \][/tex]

3. Compare LHS and RHS:

LHS:
[tex]\[ \frac{\cos^2 \beta - \cos \beta + 2}{\sin^2 \beta} \][/tex]

RHS:
[tex]\[ 2 + 4 \cot^2 \beta = 2 + 4 \frac{\cos^2 \beta}{\sin^2 \beta} \][/tex]

Rewrite RHS with the common denominator [tex]\(\sin^2 \beta \)[/tex]:
[tex]\[ 2 + 4 \frac{\cos^2 \beta}{\sin^2 \beta} = \frac{2 \sin^2 \beta + 4 \cos^2 \beta}{\sin^2 \beta} \][/tex]

Now, the comparison is between:
[tex]\[ \frac{\cos^2 \beta - \cos \beta + 2}{\sin^2 \beta} \quad \text{and} \quad \frac{2 \sin^2 \beta + 4 \cos^2 \beta}{\sin^2 \beta} \][/tex]

4. Conclusion:

Upon simplification, the fractions on both sides are not equal, and therefore:

[tex]\[ \frac{(\cos^2 \beta - \cos \beta + 2)}{\sin^2 \beta} \neq 2 + 4 \cot^2 \beta \][/tex]

Hence, the given equation is not an identity. The left-hand side does not equate to the right-hand side for all values of [tex]\(\beta\)[/tex].