## student1988 3 years ago Write the expression in the standard form a + bi. (View my question to see it written, sorry for the inconvenience)

1. student1988

|dw:1352848428519:dw|

2. student1988

That's raised to the fourth power.. I got -4. Can someone tell me if i am correct? :)

3. asnaseer

4. student1988

Is it wrong? i used De Moivre's Theorem

5. asnaseer

so did you first convert it to the form $$e^{i\theta}$$?

6. student1988

but i wasn't sure if it was right because the complex number i disappeared!

7. student1988

Not sure what you mean by that

8. asnaseer

your answer is correct - I am just making sure you used this way of getting to the answer rather than trying to expand the braces with the fourth power :)

9. student1988

|dw:1352848854469:dw|

10. student1988

i used this form

11. asnaseer

the method I used was to first convert it as follows:$(\sqrt{2}(\cos(3\pi/4)+i\sin(3\pi/4))^4=(\sqrt{2}e^{i3\pi/4})^4$

12. student1988

oh, i haven't seen this form. Could you tell me where I can read on this form?

13. asnaseer

it uses the identity:$e^{i\theta}=\cos(\theta)+i\sin(\theta)$

14. asnaseer
15. student1988

Euler's Formula. Thanks, i'll read it! Thank you! :)

16. asnaseer

Sorry - wrong link, I meant this one: http://en.wikipedia.org/wiki/Euler%27s_formula

17. asnaseer

yup - you got it!