Trig Equation Fe0B13
1. **State the problem:** Solve the equation $$1 + \frac{\sin x}{\cos x} = \frac{\cos x}{1 - \sin x}$$ for $x$.
2. **Rewrite the equation:** Note that $\frac{\sin x}{\cos x} = \tan x$, so the left side is $1 + \tan x$.
3. **Express both sides with common denominators:**
Left side: $$1 + \frac{\sin x}{\cos x} = \frac{\cos x}{\cos x} + \frac{\sin x}{\cos x} = \frac{\cos x + \sin x}{\cos x}$$
Right side is already $$\frac{\cos x}{1 - \sin x}$$
4. **Set the two fractions equal:**
$$\frac{\cos x + \sin x}{\cos x} = \frac{\cos x}{1 - \sin x}$$
5. **Cross multiply:**
$$(\cos x + \sin x)(1 - \sin x) = \cos^2 x$$
6. **Expand the left side:**
$$\cos x (1 - \sin x) + \sin x (1 - \sin x) = \cos^2 x$$
$$\cos x - \cos x \sin x + \sin x - \sin^2 x = \cos^2 x$$
7. **Group terms:**
$$\cos x + \sin x - \cos x \sin x - \sin^2 x = \cos^2 x$$
8. **Use the Pythagorean identity:**
$$\sin^2 x + \cos^2 x = 1 \implies \cos^2 x = 1 - \sin^2 x$$
9. **Substitute $\cos^2 x$:**
$$\cos x + \sin x - \cos x \sin x - \sin^2 x = 1 - \sin^2 x$$
10. **Add $\sin^2 x$ to both sides:**
$$\cos x + \sin x - \cos x \sin x = 1$$
11. **Rewrite:**
$$\cos x + \sin x - \cos x \sin x = 1$$
12. **Isolate terms:**
$$\cos x + \sin x = 1 + \cos x \sin x$$
13. **Try to find solutions by inspection:**
- If $x = 0$, then $\cos 0 = 1$, $\sin 0 = 0$, left side $1 + 0 = 1$, right side $1 + 1*0 = 1$, true.
- If $x = \frac{\pi}{2}$, $\cos \frac{\pi}{2} = 0$, $\sin \frac{\pi}{2} = 1$, left side $0 + 1 = 1$, right side $1 + 0*1 = 1$, true.
14. **General solution:** The equation holds for $x = n\pi$ and $x = \frac{\pi}{2} + n\pi$ where $n$ is any integer.
**Final answer:** $$x = n\pi \quad \text{or} \quad x = \frac{\pi}{2} + n\pi, \quad n \in \mathbb{Z}$$