√12х48х3=√12х3 х √48= √36 х √12х4= 6 х 2√12=12√12 = 24√3
Cosx=4/√17
sinx=-√(1-cos²x)=-√(1-16/17)=-1/√17
tgx=sinx/cosx=-1/√17:4/√17=1/√17*√17/4=-1/4
2sin4x≤√2
sin4x≤√2/2
3π/4+2πn≤4x≤9π/4+2πn
3π/16+πn/2≤x≤9π/16+πn/2
x∈[3π/16+πn/2;9π/16+πn/2,n∈z]
(m-n)^2+4mn m^2-2mn+n^2+4mn (m+n)^2