Question

Express M=cos3A + cos A and N = sin3A + sin A as a product form​

Answer 1

2cosAcos2A, 4sinAcos^2A

Explanation:

cos3A+cosA

2cos((3A+A)/2)cos((3A-A)/2)

2cos(4A/2)cos(2A/2)

2cosAcos2A

sin3A+sinA

2sin((3A+A)/2)cos((3A-A)/2)

2sin(4A/2)cos(2A/2)

2sin2AcosA

4sinAcos^2A