Question

Evaluate ((e^(ix) + e^(-ix)) / 2) + ((e^(ix) + e^(-ix)) / 2i) where i=√-1

Answer 1

-icosx(i+1)

Answer 2

could you explain to me how you got there?

Answer 3

e^ix is
cosx + isinx
e^(-ix) is cosx - isinx
so their sum is 2cosx

Answer 4

so its
cosx + (cosx)/i

Answer 5

oh okay. thanks a lot! we never learned that in class =/

Answer 6

u dint know this formula?

Answer 7

no i didn't. i guess i should have googled it first, it was the first page

Answer 8

see shall i teach u things abt complex nos??

Answer 9

I think I've got the rest, at least the ones that I'm being tested on. Could you teach me arcsin relationships with sin and stuff?

For example, tan(arcsin x +arccosx)for x is equal to or between 0 and 1. How would I start?

Answer 10

ur answer is infinity

Answer 11

There's no answer for x where x is equal to or between 0 and 1?

Answer 12

no i dont think so
cos arcsinx + arccosx = pi/2 for all values of x
so its tan (pi/2)

Answer 13

Oh right I get it, thank you so much!

Answer 14

no prob