cos2a-1+2sin^2a怎么化简哦

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cos2a-1+2sin^2a怎么化简哦cos2a-1+2sin^2a怎么化简哦cos2a-1+2sin^2a怎么化简哦cos2a=cos(a+a)=cosa*cosa-sina*sina=(1-si

cos2a-1+2sin^2a怎么化简哦
cos2a-1+2sin^2a
怎么化简哦

cos2a-1+2sin^2a怎么化简哦
cos 2a=cos(a+a) =cos a*cos a -sina *sina = (1-sin^2a)- sin^2a =1-2sin^2a
所以 cos2a-1+2sin^2a =1-2sin^2a-1+2sin^2a =0

1-2sin^2a=cos2a
cos2a-1+2sin^2a=0