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25 votes
I need help with this practice problem solvingThe subject is trigonometry *The red line is the instructions*

I need help with this practice problem solvingThe subject is trigonometry *The red-example-1
User KRichardson
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1 Answer

12 votes
12 votes

cis(\theta)=e^(i\theta)=cos\theta+i\cdot sin\theta

Then we have:


\begin{gathered} [3√(3)\cdot cis((\pi)/(8))\rbrack\cdot[3√(5)\cdot cis((2\pi)/(3))\rbrack=(3√(3)\cdot3√(5))e^{i(\pi)/(8)}\cdot e^{i(2\pi)/(3)} \\ [3√(3)\cdot cis((\pi)/(8))\rbrack\cdot[3√(5)\cdot cis((2\pi)/(3))\rbrack=9√(15)e^{i(19\pi)/(24)} \\ [3√(3)\cdot cis((\pi)/(8))\rbrack\cdot[3√(5)\cdot cis((2\pi)/(3))\rbrack=9√(15)cis((19\pi)/(24)) \end{gathered}

User Keeg
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