cos80°cos20°+sin100°sin380°=?
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cos80°cos20°+sin100°sin380°=?cos80°cos20°+sin100°sin380°=?cos80°cos20°+sin100°sin380°=?sin100=sin(18
cos80°cos20°+sin100°sin380°=?
cos80°cos20°+sin100°sin380°=?
cos80°cos20°+sin100°sin380°=?
sin100=sin(180-100)=sin80
sin380=sin(360+20)=sin20
cos80°cos20°+sin100°sin380°
=cos80cos20+sin80sini20
=cos(80-20)
cos60
=1/2
公式:cos(a-b)=cosacosb+sinasinb
cos80°cos20°+sin100°sin380°=?
cos20°-cos40°-cos80°=
cos20°cos40°cos80°=?
计算cos20°cos40°cos80°
化简cos20°cos40°cos60°cos80°
cos20°*cos40°*cos60°*cos80°=
cos20°cos40°cos60°cos80°是多少
不查表求:cos20°*cos40°*cos60°*cos80°=
cos20°cos10°-cos70°cos80°
化简cos20°-cos40°-cos80°等于?
cos20°cos40°cos80°怎么算
cos20°cos40°cos80°的值、急
cos20°-cos40°-cos80°的值为?
cos20°cos40°cos80°的值是
计算cos20°cos40°cos80°=多少
cos20°×cos40°×cos80°=______
cos20°+cos40°+cos80°=______
cos100°cos20°-sin100°sin20° 怎么算啊