Prove Identity
1. **State the problem:** We want to prove the identity
$$\frac{1-\sin\theta}{\cos\theta} = 3\cot\theta$$
2. **Recall definitions:**
- Recall that \(\cot\theta = \frac{\cos\theta}{\sin\theta}\).
3. **Manipulate the left-hand side (LHS):**
Start with
$$\frac{1 - \sin\theta}{\cos\theta}$$
4. **Check if the right-hand side (RHS) can be rewritten:**
Given RHS is
$$3\cot\theta = 3\frac{\cos\theta}{\sin\theta} = \frac{3\cos\theta}{\sin\theta}$$
5. **Compare LHS and RHS:**
- To prove equality, cross-multiply or simplify.
Multiply both sides by \(\cos\theta\sin\theta\):
$$ (1 - \sin\theta) \sin\theta = 3\cos^2\theta $$
6. **Expand the left side:**
$$\sin\theta - \sin^2\theta = 3\cos^2\theta$$
7. **Use Pythagorean identity:**
Recall that
$$\sin^2\theta + \cos^2\theta = 1 \implies \cos^2\theta = 1 - \sin^2\theta$$
8. **Substitute into equation:**
$$\sin\theta - \sin^2\theta = 3(1 - \sin^2\theta)$$
Expand the right side:
$$\sin\theta - \sin^2\theta = 3 - 3\sin^2\theta$$
9. **Bring all terms to one side:**
$$\sin\theta - \sin^2\theta - 3 + 3\sin^2\theta = 0$$
Simplify:
$$\sin\theta + 2\sin^2\theta - 3 = 0$$
10. **Check if this holds for all \(\theta\):**
This is not an identity true for all \(\theta\). Since the equation does not simplify to a tautology, the original statement is false in general.
**Final conclusion:**
The given equation
$$\frac{1 - \sin\theta}{\cos\theta} = 3\cot\theta$$
is not an identity true for all \(\theta\). It is therefore not generally true.
**If this was a problem to prove, please check the original expression as the equality does not hold as stated.**