化简求值:cos10°*cos20°*cos40°*cos80°*cos160°

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化简求值:cos10°*cos20°*cos40°*cos80°*cos160°

cos10°*cos20°*cos40°*cos80°*cos160°
=32sin10°*cos10°*cos20°*cos40°*cos80°*cos160°/32sin10°
=16sin20°*cos20°*cos40°*cos80°*cos160°/32sin10°
=8sin40°*cos40°*cos80°*cos160°/32sin10°
=4sin80°*cos80°*cos160°/32sin10°
=2sin160°*cos160°/32sin10°
=sin320°/32sin10°
=-sin40°/32sin10°