1) 3Sin²x -4(1-Sin²x) = 2*1
3Sin²x -4 +4Sin²x = 2(Sin²x + Cos²x)
3Sin²x -4 +4Sin²x - 2Sin²x - 2Cos²x = 0
5Sin²x -4 - 2(1-Sin²x) = 0
5Sin²x -4 -2 + 2Sin²x = 0
7Sin²x = 6
Sinx = +-√(6/7)
х = (-1)^n arcSin(+-6/7) + nπ, n ∈Z
2) Ctgx ≥ -3/4
0 + πk < x ≤ arcCtg(-3/4) + πk, k ∈Z