sin(π/4+α)sin(π/4-α)=1/6,α∈(0.π/2),求:sin4α的值
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sin(π/4+α)sin(π/4-α)=1/6,α∈(0.π/2),求:sin4α的值
sin(π/4+α)sin(π/4-α)=1/6,α∈(0.π/2),求:sin4α的值
sin(π/4+α)sin(π/4-α)=1/6,α∈(0.π/2),求:sin4α的值
sin(π/4+α)sin(π/4-α)
=-0.5[cos(π/2) --cos(2α)]
=0.5cos(2α)
=1/6
cos(2α)=1/3
sin(2α)=2根号2/3
sin4α=2sin2α*cos2α
=4根号2/9