sin(派/4+x)cos(派/4+x)=1/6 x属于(90,180) 求cos2x和sin4x
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sin(派/4+x)cos(派/4+x)=1/6 x属于(90,180) 求cos2x和sin4x
sin(派/4+x)cos(派/4+x)=1/6 x属于(90,180) 求cos2x和sin4x
sin(派/4+x)cos(派/4+x)=1/6 x属于(90,180) 求cos2x和sin4x
sin(派/4+x)cos(派/4+x)
=1/2sin(2x+π/2)
=1/2cos2x=1/6
cos2x=1/3
x属于(90,180) 2x属于(180,360) sin2x