1. **State the problem:** Prove the trigonometric identity $$\frac{\cos x}{1-\sin x} = \tan x$$.
2. **Recall the formulas and rules:**
- $$\tan x = \frac{\sin x}{\cos x}$$
- Use conjugate multiplication to simplify fractions involving expressions like $$1-\sin x$$.
3. **Start with the left-hand side (LHS):**
$$\frac{\cos x}{1-\sin x}$$
Multiply numerator and denominator by the conjugate of the denominator $$1+\sin x$$:
$$\frac{\cos x}{1-\sin x} \times \frac{1+\sin x}{1+\sin x} = \frac{\cos x (1+\sin x)}{(1-\sin x)(1+\sin x)}$$
4. **Simplify the denominator using difference of squares:**
$$(1-\sin x)(1+\sin x) = 1 - \sin^2 x$$
5. **Use the Pythagorean identity:**
$$1 - \sin^2 x = \cos^2 x$$
6. **Substitute back:**
$$\frac{\cos x (1+\sin x)}{\cos^2 x}$$
7. **Simplify the fraction by canceling one $$\cos x$$:**
$$\frac{\cancel{\cos x} (1+\sin x)}{\cancel{\cos x} \cos x} = \frac{1+\sin x}{\cos x}$$
8. **Rewrite the right-hand side (RHS) $$\tan x$$ in terms of sine and cosine:**
$$\tan x = \frac{\sin x}{\cos x}$$
9. **Check if LHS equals RHS:**
LHS is $$\frac{1+\sin x}{\cos x}$$, RHS is $$\frac{\sin x}{\cos x}$$.
They are not equal as stated, so the original identity $$\frac{\cos x}{1-\sin x} = \tan x$$ is incorrect.
10. **Check if the identity might be $$\frac{\cos x}{1-\sin x} = \sec x + \tan x$$ instead:**
Recall that $$\sec x + \tan x = \frac{1}{\cos x} + \frac{\sin x}{\cos x} = \frac{1+\sin x}{\cos x}$$, which matches our simplified LHS.
**Final conclusion:** The correct identity is $$\frac{\cos x}{1-\sin x} = \sec x + \tan x$$, not $$\tan x$$.
**Answer:** The given identity is false; the correct identity is $$\frac{\cos x}{1-\sin x} = \sec x + \tan x$$.
Trig Identity 6976A7
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