SOLUTION: Evaluate and express your answer in trigonometric form: 3(cos π/3 + i sin π/3)*4(cos π/12 + i sin π/12) I'm sorry if that is hard to read. I couldn't get the formula plot

Algebra ->  Trigonometry-basics -> SOLUTION: Evaluate and express your answer in trigonometric form: 3(cos π/3 + i sin π/3)*4(cos π/12 + i sin π/12) I'm sorry if that is hard to read. I couldn't get the formula plot      Log On


   



Question 1173366: Evaluate and express your answer in trigonometric form:
3(cos π/3 + i sin π/3)*4(cos π/12 + i sin π/12)
I'm sorry if that is hard to read. I couldn't get the formula plotting system to work.

Answer by ikleyn(52932) About Me  (Show Source):
You can put this solution on YOUR website!
.

Use the basic formula for multiplying complex numbers in trigonometric form


    if    z%5B1%5D = a%2A%28cos%28alpha%29+%2B+i%2Asin%28alpha%29%29+

    and

          z%5B2%5D = b%2A%28cos%28beta%29+%2B+i%2Asin%28beta%29%29,

then


    z%5B1%5D%2Az%5B2%5D = a%2Ab%2A%28cos%28alpha%2Bbeta%29+%2B+i%2Asin%28alpha%2Bbeta%29%29.


It gives, in your case, for the product the ANSWER


    12%2A%28cos%28pi%2F3%2Bpi%2F12%29+%2B+i%2Asin%28pi%2F3%2Bpi%2F12%29%29 = 12%2A%28cos%285pi%2F12%29+%2B+i%2Asin%285pi%2F12%29%29.



If you want  EVALUATE  it further, calculate cos%285pi%2F12%29  and  sin%285pi%2F12%29,  using your calculator.

Solved.

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On complex numbers, see introductory lessons
    - Complex numbers and arithmetical operations on them
    - Complex plane
    - Addition and subtraction of complex numbers in complex plane
    - Multiplication and division of complex numbers in complex plane

    - Solved problems on taking roots of complex numbers
    - Solved problems on arithmetic operations on complex numbers
    - Solved problem on taking square root of complex number
in this site.

Also, you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Complex numbers".


Save the link to this textbook together with its description

Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson

into your archive and use when it is needed.