Question

Prove that cos^2A+sin^2A.cos2B=cos^2B+sin^2B.cos2A​

Answer 1

Notice that both sides of the equation have a similar form. If we ignore angle functions we end up with,

$A+A\cdot B=B+B\cdot A$

That is true if condition $A=B$ is met.

Otherwise it is false.

Hope this helps.

r3t40