cos2a/cos(a-45度)=-1/2,则sina-cosa=?
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![cos2a/cos(a-45度)=-1/2,则sina-cosa=?](/uploads/image/z/3926907-27-7.jpg?t=cos2a%2Fcos%28a-45%E5%BA%A6%29%3D-1%2F2%2C%E5%88%99sina-cosa%3D%3F)
cos2a/cos(a-45度)=-1/2,则sina-cosa=?
cos2a/cos(a-45度)=-1/2,则sina-cosa=?
cos2a/cos(a-45度)=-1/2,则sina-cosa=?
(cos²a-sin²a)/(cosa cos45°+sinasin45°)=-1/2
√2(cos²a-sin²a)/(cosa +sina)=-1/2
√2(cosa-sina)*(cosa+sina)/(cosa+sina)=-1/2
√2(cosa-sina)=-1/2
sina-cosa= √2/4