Question

Prove that Cos³A.cos3A + sin³A.sin3A =cos³2A

Answer 1

Answer:

proved

Step-by-step explanation:

• use cos2A =cos^2A - sin^2A and
• Sin 3A = 3 Sin A - 4 sin³A
• Cos 3A = 4 Cos³A - 3 Cos A