" cos theos B cos C as the sum of four cosines."

Express 4 cos A cos B cos C as the sum of four cosines.

Express 4 sin A cos B cos C as the sum of four sines.

Using the fact that sin (A +B) = sin A.cos B+ cos A sin B and the differentiation, obtain the sum formula for cosines.

Using the fact that sin (A + B) = sin A cos B + cos A sin B and the differentiation, obtain the sum formula for cosines.

Using the fact the that sin (A+B)= sin A cos B+ cos A sin B and the differentiation, obtain the sum formula for cosines.

Using the fact the that sin (A+B)= sin A cos B+ cos A sin B and the differentiation, obtain the sum formula for cosines.

Using the fact the that sin (A+B)= sin A cos B+ cos A sin B and the differentiation, obtain the sum formula for cosines.

Express each of that as the sum or difference of cosines and sines: cos 75^@Cos 15^0

Express each of that as the sum or difference of cosines and sines: cos75^(@)cos15^(0)

Express cos2A+cos2B+cos2C+cos2(A+B+C) as the product of three cosines.