" 09."cos40^(@)+cos80^(@)+cos160^(@)=

Prove that cos40^(@) cos80^(@) cos160^(@) = -1/8

cos 20^(@) cos 40^(@) cos 80^(@)=

Prove that: i) cos10^(@)cos30^(@)cos50^(@)cos70^(@)=3/16 ii) cos20^(@)cos40^(@)cos60^(@)cos80^(@)=1/16 iii) 4cos12^(@)cos48^(@)cos72^(@)=cos36^(@) iv) cos40^(@) cos80^(@)cos160^(@)=-1/8

Prove that: i) cos10^(@)cos30^(@)cos50^(@)cos70^(@)=3/16 ii) cos20^(@)cos40^(@)cos60^(@)cos80^(@)=1/16 iii) 4cos12^(@)cos48^(@)cos72^(@)=cos36^(@) iv) cos40^(@) cos80^(@)cos160^(@)=-1/8

cos 40^(@) + cos 80^(@) + cos 160^(@) =

Prove that: cos40^(@)cos80^(@)cos160^(@)=-(1)/(8)

If sin2A=2sinA cosAand sin20^(@)=K, " then the value of " cos20^(@)cos80^(@)cos160^(@) =__________.

The value of cos40^(@)+cos80^(@)+cos160^(@) is

if sin2A=2sin A cos A and sin20^(@)=K then the value of cos20^(@)cos40^(@)cos80^(@)cos160^(@)-