20xx安徽省歷年中考數(shù)學(xué)題目考點(已改無錯字)
2025-04-03 21 本頁面
【正文】 ^2+B^2)^(1/2)cos(αt)，tant=A/B 降冪公式 sin^2(α)=(1cos(2α))/2=versin(2α)/2 cos^2(α)=(1+cos(2α))/2=covers(2α)/2 tan^2(α)=(1cos(2α))/(1+cos(2α)) 推導(dǎo)公式 tanα+cotα=2/sin2α tanαcotα=2cot2α 1+cos2α=2cos^2α 1cos2α=2sin^2α 1+sinα =(sinα/2+cosα/2)^2 =2sina(1sin2a)+(12sin2a)sina =3sina4sin3a cos3a =cos(2a+a) =cos2acosasin2asina =(2cos2a1)cosa2(1sin2a)cosa =4cos3a3cosa sin3a =3sina4sin3a =4sina(3/4sin2a) =4sina[(√3/2)2sin2a] =4sina(sin260176。sin2a) =4sina(sin60176。+sina)(sin60176。sina) =4sina_2sin[(60+a)/2]cos[(60176。a)/2]_2sin[(60176。a)/2]cos[(60176。a)/2] =4sinasin(60176。+a)sin(60176。a) cos3a =4cos3a3cosa =4cosa(cos2a3/4) =4cosa[cos2a(√3/2)2] =4cosa(cos2acos230176。) =4cosa(cosa+cos30176。)(cosacos30176。) =4cosa_2cos[(a+30176。)/2]cos[(a30176。)/2]_{2sin[(a+30176。)/2]sin[(a30176。)/2]} =
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