Solve the following trigonometric equations: `sin(theta/2)=-1` (ii) `cos(3theta)/2=1/2` (iii) `t a n(2/3theta)=sqrt(3)`

Explanation

Let's solve the given trigonometric equations step by step.

### (i) Solve `sin(theta/2) = -1`

1. **Identify the angle**: We know that `sin(theta) = -1` occurs at `theta = 3π/2 + 2nπ`, where `n` is any integer.

2. **Set up the equation**: Since we have `sin(theta/2) = -1`, we can equate `theta/2` to `3π/2 + 2nπ`.

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