p302 q19
given
evaluate:
my working
and stuck.
thanks!
Hello
Let :
Because you're given the formula above, divide by (because it's different to 0, we can do it)
Therefore :
Now, it would be great if it could be simplified.
You can notice that it looks like a lot de Moivre's formula :
So we're gonna make a transform... According to the unit circle (or to your lesson) :
Great !
Therefore
Now we can apply de Moivre's formula :
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Conclude