sin2a=1/3 a∈(π/4,3/4π)则tana=?

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sin2a=1/3a∈(π/4,3/4π)则tana=?sin2a=1/3a∈(π/4,3/4π)则tana=?sin2a=1/3a∈(π/4,3/4π)则tana=?解析:已知a∈(π/4,3/4π

sin2a=1/3 a∈(π/4,3/4π)则tana=?
sin2a=1/3 a∈(π/4,3/4π)则tana=?

sin2a=1/3 a∈(π/4,3/4π)则tana=?
解析:
已知a∈(π/4,3/4π),那么:2a∈(π/2,3π/2)
又sin2a=1/3>0,所以:2a∈(π/2,π)
那么:cos2a=-根号(1-sin²2a)=-(2根号2)/3
所以:tana=(1-cos2a)/sin2a=(1+2根号2/3)÷(1/3)=3+2根号2