[Risolto] Sistema

* (2*sin^2(x) - cos(x) - 1 < 0) & (1 - tg(x) <= 0) & (0 <= x < 2*π) ≡
≡ (2*(1 - cos^2(x)) - cos(x) - 1 < 0) & (1 - tg(x) <= 0) & (0 <= x < 2*π) ≡
≡ (2*cos^2(x) + cos(x) - 1 > 0) & (tg(x) >= 1) & (0 <= x < 2*π)
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* 2*cos^2(x) + cos(x) - 1 > 0 ≡
≡ (cos(x) + 1)*(cos(x) - 1/2) > 0 ≡
≡ (cos(x) < - 1) & (cos(x) < 1/2) oppure (cos(x) > - 1) & (cos(x) > 1/2) ≡
≡ (cos(x) > 1/2)
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* (cos(x) > 1/2) & (0 <= x < 2*π) ≡
≡ (0 <= x < π/3) oppure (5*π/3 < x < 2*π)
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* (tg(x) >= 1) & (0 <= x < 2*π) ≡
≡ (π/4 <= x < π/2) oppure (5*π/4 <= x < 3*π/2)
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* (0 <= x < π/3) & (π/4 <= x < π/2) ≡ (π/4 <= x < π/3)
* (0 <= x < π/3) & (5*π/4 <= x < 3*π/2) ≡ (insieme vuoto)
* (5*π/3 < x < 2*π) & (π/4 <= x < π/2) ≡ (insieme vuoto)
* (5*π/3 < x < 2*π) & (5*π/4 <= x < 3*π/2) ≡ (insieme vuoto)
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* (2*cos^2(x) + cos(x) - 1 > 0) & (tg(x) >= 1) & (0 <= x < 2*π) ≡
≡ π/4 <= x < π/3