A) 2sinαcosα , α =π/2.
2sinαcosα =sin2α =sin(2*π/2) =sinπ = 0.
или иначе 2sinαcosα =2sin(π/2)*cos(π/2) =2*1*0 = 0.
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B) cos(3π/2 -0,5x) =0,5 ;
-sin0,5x =0,5 ;
sin0,5x = - 0,5 ;
0,5x = (-1)^(n+1)*π/6 +π*n ,n∈Z.
x = (-1)^(n+1)*π/3 +2π*n ,n∈Z.
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C) только не sos =2sinp/2sos2p=
6 -sin2π -cosπ +2sinπ/2cos2π =6 -0 -3*(-1)+2*0/2*1 =6+3=9.