Hello, cakeboby!
You're doing great!Prove the following identity: .
Here's what I did:
. . . . .
We need some Sum-to-Product idenities:
. .
You have: .
. . . . . . .
. . . . . . .
. . . . . . .
you can factorize to continue the equation
become
and continue with sum to product identities.
for help use this: http://en.wikipedia.org/wiki/List_of...uct_identities