1. **State the problem:** Find all solutions of the equation $$2\sin^2 y = 2 + \cos y$$ on the interval $$[0, 2\pi)$$.
2. **Rewrite the equation using the Pythagorean identity:** Recall that $$\sin^2 y = 1 - \cos^2 y$$.
3. Substitute into the equation:
$$2(1 - \cos^2 y) = 2 + \cos y$$
4. Simplify the left side:
$$2 - 2\cos^2 y = 2 + \cos y$$
5. Subtract 2 from both sides:
$$2 - 2\cos^2 y - 2 = 2 + \cos y - 2$$
$$-2\cos^2 y = \cos y$$
6. Rearrange to standard quadratic form:
$$-2\cos^2 y - \cos y = 0$$
Multiply both sides by $$-1$$ to simplify:
$$2\cos^2 y + \cos y = 0$$
7. Factor the expression:
$$\cos y (2\cos y + 1) = 0$$
8. Set each factor equal to zero and solve:
- $$\cos y = 0$$
- $$2\cos y + 1 = 0$$
9. Solve $$\cos y = 0$$:
$$y = \frac{\pi}{2}, \frac{3\pi}{2}$$
10. Solve $$2\cos y + 1 = 0$$:
$$2\cos y = -1$$
$$\cos y = -\frac{1}{2}$$
11. Find $$y$$ values where $$\cos y = -\frac{1}{2}$$ on $$[0, 2\pi)$$:
$$y = \frac{2\pi}{3}, \frac{4\pi}{3}$$
12. **Final solutions:**
$$y = \frac{\pi}{2}, \frac{3\pi}{2}, \frac{2\pi}{3}, \frac{4\pi}{3}$$
These are all solutions to the equation on the interval $$[0, 2\pi)$$.
Trig Equation 1 18Df75
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