a) tgx >1
πn +π/4 < x < π/2</strong> + πn , n ∈ Z.
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x ∈ об единение интервалов ( πn +π/4 ; π/2 +πn );
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π/4 < x < π/2 ;
2πk+π/4 < x < π/2 + 2πk ;
2k*π+ π/4 < x < π/2 + 2k*π (1)
2k _четное число .
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π+ π/4 < x <3π/2 ;<br>π+ π/4 < x < π/2 </strong> + π ;
2πk+π+ π/4 < x < π/2 </strong> + π +2πk ;
(2k+1)π + π/4 < x < π/2 + </strong>(2k+1)π (2)
(2k+1)__нечетное число .
πn +π/4 < x < π/2</strong> + πn , n ∈ Z.
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б) сos x≤0 .
2πk + π/2 ≤ x ≤ 3π/2 +2πk , k∈ Z.
в) ctgx <1.<br>πk+ π/4 < x < π </strong>+πk
г) sinx ≥0 .
πk ≤ x ≤ (2k +1)π ; k∈ Z
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2πk+0 ≤ x ≤ π + 2πk ; k∈ Z.
2πk ≤ x ≤ π + 2πk ; k∈ Z.
2πk ≤ x ≤ (2k +1)π ; k∈ Z
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