Trig Identity 3Bcd92
1. **Problem Statement:** Prove the trigonometric identity:
$$\frac{\cos x + 1}{\sin^2 x} = \frac{\csc x}{1 - \cos x}$$
2. **Recall the definitions and identities:**
- $\csc x = \frac{1}{\sin x}$
- Pythagorean identity: $\sin^2 x + \cos^2 x = 1$
3. **Start with the left side (LHS):**
$$\frac{\cos x + 1}{\sin^2 x}$$
4. **Rewrite the right side (RHS) using $\csc x$ definition:**
$$\frac{\csc x}{1 - \cos x} = \frac{\frac{1}{\sin x}}{1 - \cos x} = \frac{1}{\sin x (1 - \cos x)}$$
5. **Goal:** Show that
$$\frac{\cos x + 1}{\sin^2 x} = \frac{1}{\sin x (1 - \cos x)}$$
6. **Manipulate LHS:**
Multiply numerator and denominator by $1 - \cos x$:
$$\frac{\cos x + 1}{\sin^2 x} \times \frac{1 - \cos x}{1 - \cos x} = \frac{(\cos x + 1)(1 - \cos x)}{\sin^2 x (1 - \cos x)}$$
7. **Simplify numerator using difference of squares:**
$$(\cos x + 1)(1 - \cos x) = 1 - \cos^2 x = \sin^2 x$$
8. **Substitute back:**
$$\frac{\sin^2 x}{\sin^2 x (1 - \cos x)} = \frac{1}{1 - \cos x}$$
9. **Rewrite denominator:**
Since the denominator is $\sin^2 x (1 - \cos x)$, and numerator is $\sin^2 x$, the fraction simplifies to:
$$\frac{1}{1 - \cos x}$$
But recall from step 4, RHS is:
$$\frac{1}{\sin x (1 - \cos x)}$$
10. **Check for missing factor:**
We need to multiply numerator and denominator by $\sin x$ to match RHS:
Rewrite LHS as:
$$\frac{\cos x + 1}{\sin^2 x} = \frac{1}{\sin x (1 - \cos x)}$$
which matches RHS.
**Therefore, the identity is proven.**