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?
Could you please, write your methods down.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).
I got the same answer as you.It can also be seen very easily by drawing them in the complex plane, if you've been taught that.
The two statements do not hold for all values of x1 and x2.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.