" (iv) "cos40^(@)cos100^(@)cos160^(@)=(1)/(8)

cos20^(@)+cos100^(@)+cos140^(@)=

Prove that: 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

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, cos20^(@)+cos60^(@)+cos100^(@)+cos140^(@)=(1)/(2)

Prove that cos 20^(@)cos40^(@)cos60^(@)cos80^(@)=(1)/(16)

Prove that: cos20^(@)cos40^(@)cos80^(@)=(1)/(8)

Prove that: cos20^(@)cos40^(@)cos60^(@)cos80^(@)=(1)/(16)

Prove that :cos20^(@)cos40^(@)cos60^(@)cos80^(@)=(1)/(16)

Prove that cos20^(@)cos40^(@)cos60^(@)cos80^(@)=(1)/(16)