3 arcsin(-1) -3/2 arccos(√3/2)-7,5 arctg(-1/√3)
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3 arcsin(-1) -3/2 arccos(√3/2)-7,5 arctg(-1/√3) = 3*(-π/2) -1,5*π/6 +7,5*π/6 == - 3π/2  - π/4 +5π/4 = -1,5π +π = -0,5π