若a是0～90度的角,且sin^2a+cos2a=1/4,则tana=?
人气：359 ℃ 时间：2020-02-05 08:46:37
解答
cos2a=2cos^2a-1
sin^2a+2cos^2a=5/4
因为sin^2a+cos^2a=1
所以cos^2a=1/4
sin^2a=3/4
tan^a=(sin^2a)/(cos^2a)=3
a属于0-90度
tan a=根号3
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