化简 :根号(1-sin2)
解:∵1-sin2=1-2sin1*cos1=(cos1)^2-2sin1*cos1+(sin1)^2 =(cos1-sin1)^2 ∵1≈53.7度.∴cos1>sin1 ∴原式=cos1-sin1
1-sin2 =1+2sin1*sin2 =(sin1)^2+(cos1)^2+2sin1*cos1 =(sin1+cos1)^2 =[√2sin(1+π/4)]^2 =2[sin(1+π/4)]^2
答:(sina+sin2a)/(1+cosa+cos2a) =sina+2sinacosa/cosa+1+2cos^2a-1 =sina(1+2cosa)/cosa...详情>>
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