求sin39°-sin21°/cos39°-cos21°的值急需过程,谢谢!
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求sin39°-sin21°/cos39°-cos21°的值急需过程,谢谢!求sin39°-sin21°/cos39°-cos21°的值急需过程,谢谢!求sin39°-sin21°/cos39°-co
求sin39°-sin21°/cos39°-cos21°的值急需过程,谢谢!
求sin39°-sin21°/cos39°-cos21°的值
急需过程,谢谢!
求sin39°-sin21°/cos39°-cos21°的值急需过程,谢谢!
用积化和差公式.
2cos30*sin9/-2sin30*sin9=-cos30/sin30=-根号3
(sin39° -sin21°)/(cos39°-cos21°)
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°)
(sin24°cos6°-sin66°sin6°)/(sin21°cos39°-cos21°sin39°)化简后得
cos39°cos9°+sin39°sin9°=
sin39°-sin30°cos9°/cos39°-cos30°cos9°
求sin21°+sin22°+...+sin289°的值.
cos51°cos9°-cos39°sin9°=
sin21°cos24°+cos21°sin24°
sin21°cos81°-cos21°sin81°=?
求值sin21°cos24°+cos21°sin24°过程
sin21°cos81°-sin69°cos9°
求值sin21°cos24°+cos21°sin24°过程
求值：sin21°cos81°-sin69°cos9°
sin21°cos81°+cos189°sin69°化简
sin21°cos9°+cos21°sin9°=?
求值：sin21/4π tan(-23/6π) cos1500°