Using the quadratic formula, solve for x to the nearest ten thousandth in the interval [0,2pi]

Using the quadratic formula, solve for x to the nearest ten thousandth in the interval [0,2pi]

2. 5sin^2 x-3 sin x-1=0

3. cos^2 x+2 cos x-2 =0

I really need clarification on this topic, 10 points best answer!

Please help!

Thanks!

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