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

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

Prove that cos 20^(@) cos 40^(@) cos 80^(@) = (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 : sin60^(@)cos30^(@)+cos60^(@).sin30^(@)=1

Prove that: cos20^0cos40^0cos60^0cos80^0=1/(16)

Prove that cos12^(@)+cos84^(@)+cos132^(@)+cos156^(@)=-1/2

Prove that cos20^0cos40^0cos60^0cos80^0=1/(16)dot

Statement-1: The vlaue of cos20^(@)cos40^(@)cos60^(@)cos80^(@)is1/16. Statement-2: for any theta, cos thetacos(60^(@)-theta)cos(60^(@)+theta)=1/4cos3theta

Prove that : cos 20^0cos 40^0cos 60^0cos 80^0=1/(16)

Prove that : cos30^(@).cos60^(@)-sin30^(@).sin60^(@)=0