Cosx = -
/2
x = pi - arccos /2 + 2pK
x = pi - pi/6 + 2pk
x1 = 5pi/6 + 2pk
x2= -pi + pi/6 + 2pk
x2 = -5pi/6 + 2pk
sin2x = - 1
2x = (-1)^karcsin(-1) + pK
2x= 3pi/2 + pk
x = 3pi/4 + pk/2
2ctg3x = -2
ctg3x = -2/2
ctg3x = -1
3x = arcctg(-1) + pk
3x = -arcctg1 + pk
3x = -pi/4 + pk
x = -pi/12 + pk/3
sinx <= 1/2 <br>x ∈ [ -pi - arcsin1/2 +2pk; arcsin1/2 + 2pk]
x ∈ [ -pi - pi/6 + 2pk; pi/6 + 2pk]
x ∈ [ -7pi/6 + 2pk; pi/6 + 2pk]
cosx =>-√3/2
x ∈ [arccos√3/2 + 2pk; -arccos √3/2 + 2pk]
x ∈ [ pi/6 + 2pk; -pi/6 + 2pk]