sin21°cos39°+cos21°sin39°=
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sin21°cos39°+cos21°sin39°=sin21°cos39°+cos21°sin39°=sin21°cos39°+cos21°sin39°=sin21°cos39°+cos21°sin
sin21°cos39°+cos21°sin39°=
sin21°cos39°+cos21°sin39°=
sin21°cos39°+cos21°sin39°=
sin21°cos39°+cos21°sin39°
=sin(21°+39°)
=sin60°
=√3/2
(sin39° -sin21°)/(cos39°-cos21°)
sin21°cos39°+cos21°sin39°=
(sin24°cos6°-sin66°sin6°)/(sin21°cos39°-cos21°sin39°)
求sin39°-sin21°/cos39°-cos21°的值急需过程,谢谢!
(sin24°cos6°-sin66°sin6°)/(sin21°cos39°-cos21°sin39°)化简后得
sin21°cos24°+cos21°sin24°
sin21°cos81°-cos21°sin81°=?
求值sin21°cos24°+cos21°sin24°过程
求值sin21°cos24°+cos21°sin24°过程
sin21°cos9°+cos21°sin9°=?
（cos^2 33°-cos^2 57°）／（sin21°－cos21°）
sin21 cos21等于几?精确啊
cos39°cos9°+sin39°sin9°=
cos51°cos9°-cos39°sin9°=
1.比大小：tan21°和tan31°；2.sin21°和cos21°；3.cos21°和cos22°遇到这样的题目该怎么解?2.把正整数1,2,3,4,5.按如下规律排列：12,3,4,5,6,7,8,9,10,11,12,13,14,15,.按此规律,可知第n行有多少个正整数?不只要
sin21度 cos21度 tan38度等于多少?
sin21°cos81°-sin69°cos9°
求值：sin21°cos81°-sin69°cos9°