tana=2,显然coaa不等于0;(sina+cosa)/(sina-cosa)=(tana+1)/(tana-1)=3
sinacosa=sinacosa/((sina)^2+(cosa)^2)=tana/((tana)^2+1)=2/5
sin2a-2cos2a+1=2sinacosa-2((cosa)^2-(sina)^2)+(sina)^2+(cosa)^2=2sinacosa-(cosa)^2+3(sina)^2=(2sinacosa-(cosa)^2+3(sina)^2)/((sina)^2+(cosa)^2)=(2tana-1+3(tana)^2)/((tana)^2+1)=3
已知tana=2,求 (1) (sina+cosa)/(sina-cosa) (2) sinacosa (3) sin2a-2cos2a+1
已知tana=2,求 (1) (sina+cosa)/(sina-cosa) (2) sinacosa (3) sin2a-2cos2a+1
数学人气:895 ℃时间:2020-03-27 02:03:06
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