Hi, I'm struggling with this question:
Show that
I have covered identities but I get in a huge expansion that is so confusing and from past questions tend to have a neater way of doing things.
Your help would be greatly appreciated.
D
Hi, I'm struggling with this question:
Show that
I have covered identities but I get in a huge expansion that is so confusing and from past questions tend to have a neater way of doing things.
Your help would be greatly appreciated.
D
I think that the tidiest way to do this is to use the addition formulas
Use those formulas to get
(from (2)),
(from (1)),
and therefore
(subtracting (5) from (4)).
Also,
(from (3)).
Finally, substitute the result from (7) into (6) to get your formula.
The interesting thing here is that although the formula is completely symmetrical in , and , it is necessary to break the symmetry in order to get an efficient proof (in this case, by treating the term differently from its "partners" and ).