Prove that: `\ cos A+cos3A+cos5A+cos7A=4cos A cos2A cos4A`

Prove that: cos3A+cos5A+cos7A+cos15A=4cos4A cos5A cos6A

Prove that: (cos 2A cos 3A -cos 2A cos 7A + cos A cos 10A)/("sin" 4A sin 3A - sin 2A sin 5A + sin 4A sin 7A) = cot 6A cot 5A

Prove that: cos3A+cos5A+cos7A+cos 15 A=4cos4A cos5A cos6A

Prove that: (cos 2A cos 3A-cos 2A cos 7A + cos A cos 10A)/(sin 4A sin 3A -sin 2A sin 5A + sin 4A sin 7A)= cot 6A cot 5A .

Prove that: (cos2A\ cos3A-cos2Acos7A+cos10 A cos A)/(sin4A\ sin3A-sin2A sin5A+sin4Asin7A )=cot6A\ cot5A

(cosA + cos3A + cos5A + cos7A)/(cosAcos2Acos4A)=

cos3A+cos5A+cos7A+cos15A=4cos4A cos5A cos6A

Prove that, cos3A+cos5A+cos7A+cos15A=4cos4Acos5Acos6A .

cot3A+cos5A+cos7A+cos15A=4cos4A cos5A cos6A

Prove that: (cos8A cos5A-cos12A cos9A)/(sin8A cos5A+cos12A sin9A)=tan4A