cos `10^(@)` cos `30^(@)` cos `50^(@)` cos `70^(@) =(3)/(16)`

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

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

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

Prove that: cos10^(0)cos30^(@)cos50^(@)cos70^(@)=(3)/(16)

1+ cos 10^(@) + cos 20^(@)+ cso 30^(@)=

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))

1+ cos 10^(@) + cos 20^(@)+ cos 30^(@)= ............... A) 4 cos 5^(@) cos 10^(@) cos 15^(@) B) 4 cos 10^(@) cos 20^(@) cos 30^(@) C) 4 sin 5^(@) sin 10^(@) sin 15^(@) D) 4 sin 10^(@) sin 20^(@) sin 30^(@)

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