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tan(a+b)=2/5,tan(a-90)=1/4,tan(b+90)=?
人气:148 ℃ 时间:2020-07-10 23:40:11
解答
∵tan(a+b)=2/5,tan(a-90)=1/4,
∴tan(b+90)=tan((a+b)-(a-90))
=(tan(a+b)-tan(a-90))/(1+tan(a+b)*tan(a-90))
=((2/5)-(1/4))/(1+(2/5)*(1/4))
=3/22.
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