两角和差的三角函数题目1.设(sin π/12+cos π/12)乘(sin π/12-cos π/12)=?2.化简根号(1+sin2)+根号(1-sin2)3.设f(sinX)=cos2X,那么f(1/2)=?

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两角和差的三角函数题目1.设(sinπ/12+cosπ/12)乘(sinπ/12-cosπ/12)=?2.化简根号(1+sin2)+根号(1-sin2)3.设f(sinX)=cos2X,那么f(1/2

两角和差的三角函数题目1.设(sin π/12+cos π/12)乘(sin π/12-cos π/12)=?2.化简根号(1+sin2)+根号(1-sin2)3.设f(sinX)=cos2X,那么f(1/2)=?
两角和差的三角函数题目
1.设(sin π/12+cos π/12)乘(sin π/12-cos π/12)=?
2.化简根号(1+sin2)+根号(1-sin2)
3.设f(sinX)=cos2X,那么f(1/2)=?

两角和差的三角函数题目1.设(sin π/12+cos π/12)乘(sin π/12-cos π/12)=?2.化简根号(1+sin2)+根号(1-sin2)3.设f(sinX)=cos2X,那么f(1/2)=?
1.(sin π/12+cos π/12)乘(sin π/12-cos π/12)
=(sin π/12)²-(cos π/12)²
=-cos π/6=-√3/2
2.平方得(√(1+sin2)+√(1-sin2))²
=2+2√(1-sin²2) (我粗粗一想,应该这么做,身边没草稿纸,下面就靠你自己了)
3.当sinX=0.5时,X=30°.
因为f(sinX)=cos2X,所以f(1/2)=cos2*30°=0.5.