1) cos(x-1)=√3/2 2)cosx>√2/2 , x ∈ ( 0 ; π/2 )

$1) \: \cos(x - 1) = \frac{ \sqrt{3} }{2} \\ \\ a) \: x - 1 = \frac{\pi}{6} + 2\pi \: n \\ x = \frac{\pi}{6} + 1 + 2\pi \: n \\ \\ b) \: x - 1 = - \frac{\pi}{6} + 2\pi \: n \\ x = - \frac{\pi}{6} + 1 + 2\pi \: n \\$

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\frac{ \sqrt{2} }{2} \\ \\ - \frac{\pi}{4} + 2\pi \: n < x < \frac{\pi}{4} + 2\pi \: n \\ \\ " alt="2) \: \cos(x) > \frac{ \sqrt{2} }{2} \\ \\ - \frac{\pi}{4} + 2\pi \: n < x < \frac{\pi}{4} + 2\pi \: n \\ \\ " align="absmiddle" class="latex-formula">
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