" (i) "cos20^(@)cos40^(@)cos80^(@)=(1)/(8)

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

Prove that a) (sin3A + sinA)sinA+(cos3A-cosA) cosA=0 b) cos20^(@)cos40^(@)cos80^(@)=1/8

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

Prove that cos 20^(@) cos 40^(@) cos 80^(@) = (1)/(8).

Prove that a) (sin3A + sinA)sinA+(cos3A-cosA) cosA=0 b) cos20^(@)cos40^(@)cos80^(@)=1/8 c) (sin8thetacostheta-sin6thetacos3theta)/(cos2thetacostheta-sin3thetasin4theta) = tan2theta

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

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

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

(a) If f(x)=(x-1)/(x+1) then show that. (i) f((1)/(x))=-f(x) (ii) f(-(1)/(x))=-(1)/(f(x)) . (b) Prove that cos20^(@)cos40^(@)cos80^(@)=1//8

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