`cos 10^(@) cos 30^(@) cos 50^(@) cos 70^(@) = `

The value of 16cos 10^(@) cos30^(@) cos50^(@)cos70^(@) "is"

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 (i) sin 70^(@) cos 10^(@) -cos 70^(@) sin 10^(@) =(sqrt(3))/(2) (ii) cos 50^(@) cos 10^(@) -sin 50^(@) sin 10^(@) =(1)/(2) (ii) cos 80^(@) cos 20^(@) + sin 80^(@) sin 20^(@) =(1)/(2) (iv) sin 36^(@) cos 9^(@) + cos 36^(@) sin 9^(@) =(1)/(sqrt(3))

Prove that cos10^(@)cos30^(@)cos50^(@)cos70^(@)=(3)/(16)

Prove that cos10^(@)cos30^(@)cos50^(@)cos70^(@)=(3)/(16)

cos10^(0)cos30^(0)cos50^(@)cos70^(0)

1 + cos 10^(@) + cos 20^(@) + cos30^(@) =