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Specialist Mathematics ยท Unit 2 ยท Complex arithmetic and algebra ยท Complex arithmetic using polar form

Understand and use multiplication, division of complex numbers in polar form and the geometric interpretation of these. ๐‘ง1 ๐‘ง2 = ๐‘Ÿ1 ๐‘Ÿ2 cis(๐œƒ1 + ๐œƒ2) ๐‘ง1 ๐‘ง2 = ๐‘Ÿ 1 ๐‘Ÿ 2 cis(๐œƒ1 โˆ’ ๐œƒ2)

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Question 1

Consider the complex numbers $z_1 = 6\operatorname{cis}\left(\frac{\pi}{3}\right)$ and $z_2 = 2\operatorname{cis}\left(\frac{\pi}{4}\right)$. (a) Determine the value of $w = z_1 z_2$ in polar form. (2 marks) (b) Determine the value of $u = \frac{z_1}{z_2}$ in polar form. (2 marks)

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Question 2

Consider the complex numbers $z_1 = 3\,\text{cis}\left(\frac{\pi}{4}\right)$ and $z_2 = 2\,\text{cis}\left(\frac{\pi}{3}\right)$. a) Determine $z_1 z_2$ in polar form. (1 mark) b) Determine $\frac{z_1}{z_2}$ in polar form. (1 mark) c) Verify your result from part (b) by converting both $z_1$ and $z_2$ to Cartesian form, performing the division, and converting the result back to polar form. (1 mark)

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Question 3

Use the given polar forms to determine the value of $w$.

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