Prove that: `cos Acos(60^0-A)cos(60^0+A)=1/4cos3A`

Prove that : cos Acos(60-A)cos(60+A)=1/4cos3A

Prove that :cos A cos(60-A)cos(60+A)=(1)/(4)cos3A

Prove that: cos A cos(60^(@)-A)cos(60^(@)+A)=(1)/(4)cos3A

Prove that: cosA. Cos(60^(@)+A)cos(60^(2)-A)=1/4 cos3A

If A=30^(@) , show that : 4cosAcos(60^(@)-A)*cos(60^(@)+A)=cos3A

Prove that: (i) cos A cos(60^(@)-A)cos (60^(@)+A)=(1)/(4)cos 3A (ii) "tan" A+"tan"(60^(@)+A)-"tan"(60^(@)-A)=3 tan 3A .

Prove that cos^3A+cos^3(120^0+A)+cos^3(240^0+A)=3/4cos3A

Prove that cos(60^(@)+A) + cos(60^(@)-A)-cosA=0

(ii) Prove cos x cos(60-x)cos(60+x)=(1)/(4)cos3x

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