cis(x1 - x2) - cis(x2 - x1) = 2cos(x1 - x2)
The Attempt at a Solution
Cis is a sin-and-cos summation. Shortly,
cisx = cosx + isinx
How can you prove the statement?
You're going to have a hard time proving that, unless my math is bad today (a very real possibility... I've been making some pretty bad gaffes lately...)
I get that it should come out to 2isin(x1-x2).
It can also be seen very easily by drawing them in the complex plane, if you've been taught that.
Could you please, write your methods down.
The following must be true to prove the statement
cos(x1 - x2) = cos(x2 - x1)
sin(x1 - x2) = -sin(x1 - x2)
If the above statements hold, then the original statement can be proven true.
I'm a reasonable person, by my own estimation, but I am unable to see into his/her mind to see what he/she means to do.