作业帮cos100°-cos40°=（-sin70°）怎么从左边推算到右边的?
来源：学生作业帮助网 编辑：作业帮 时间：2024/11/26 05:40:19
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cos100°-cos40°=（-sin70°）怎么从左边推算到右边的?
cos100°-cos40°=（-sin70°）怎么从左边推算到右边的?
cos100°-cos40°=（-sin70°）怎么从左边推算到右边的?
cos100°-cos40°
=cos(70°+30°)-cos(70°-30°)
=cos70°cos30°-sin70°sin30°-cos70°cos30°-sin70°sin30°
=-2sin30°sin70°
=-2*(1/2)*sin70°
=-sin70°
cos100°cos40°+sin80°sin40°
化简cos100°cos40°+sin80°sin40°
cos100°-cos40°=（-sin70°）怎么从左边推算到右边的?
cos100度-cos40度+sin70度=?
cos100°-cos40°=（-sin70°）怎么从左边推算到右边的?需要具体的步骤
cos20°—cos40°+cos60°+cos100°的值答案为1/2
cos20°+cos100度+cos140度=?
cos100°的绝对值等不等于-cos100°
求值 1/cos100°^2-3/cos100°^2
设M＝cos20°×cos40°×cos60°×cos80°×cos100°×cos120°×cos140°×cos160°,求证：M＝1/256
化简√(1-sin 80°)的结果是A.sin40°+cos40° B.sin40°-cos40° C.cos40°-sin40° D.-sin40°-cos40°
根号(1-2sin40°cos40°)/ (cos40°-根号1-sin^2 50°)
tan100°=m cos100°=?用m表示
1/cos80°(3/sin²40°-1/cos40°)=?
化简：根号下1-2sin40°*cos40°/cos40°- 根号下1-sin^2 50°
cos20°-cos40°-cos80°=
sin40°cos40°=sin80°?
cos20°cos40°cos80°=?