cos80°cos70°-sin80sin70
=cos(80°+70°)
=cos150°
=cos(180°-30°)
=-cos30°
=-√3/2 这是一道和角公式题cos(x+B）=cosXcosB-sinXsinB
计算题cos80°cos70°-sin80sin70
3个回答
相关问题
-
求值：（2sin80°-cos70°）/cos20°
-
计算：cos(70°+α)sin(170°-α)-sin(70°+α)cos(10°+α)
-
计算：sin20°cos40°+sin70°cos50°
-
sin70°cos25°-sin25°cos70°
-
把cos80°-sin70°化成积的形式.
-
cos70°cos25°+sin70°sin25°等于
-
sin80°cos20°-cos80°sin20°求解此题
-
cos(70)cos(40)+sin(70)sin(40)是多少
-
请证明(sin10)(cos10)(cos30)(cos50)(cos70)=(3/16)*(cos80),thx la
-
cos80°cos35°+sin80°sin35°=______．