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Question
Math
Posted 8 months ago

Given the complex number z=3eiπ/3iz=\sqrt{3} e^{\wedge} i \pi / 3-i.
a) Determine the number zz in rectangular form. b) Determine the modulus and main argument of the number z17z^{\wedge} 17
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Answer from Sia
Posted 8 months ago
Solution by Steps
step 1
Given the complex number z=3eiπ/3iz = \sqrt{3} e^{i \pi / 3} - i, we need to convert it to rectangular form
step 2
The term 3eiπ/3\sqrt{3} e^{i \pi / 3} can be expressed in rectangular form using Euler's formula: eiθ=cos(θ)+isin(θ)e^{i \theta} = \cos(\theta) + i \sin(\theta)
step 3
For θ=π/3\theta = \pi / 3, we have cos(π/3)=12\cos(\pi / 3) = \frac{1}{2} and sin(π/3)=32\sin(\pi / 3) = \frac{\sqrt{3}}{2}. Thus, 3eiπ/3=3(12+i32)=32+i32\sqrt{3} e^{i \pi / 3} = \sqrt{3} (\frac{1}{2} + i \frac{\sqrt{3}}{2}) = \frac{\sqrt{3}}{2} + i \frac{3}{2}
step 4
Subtracting ii from 32+i32\frac{\sqrt{3}}{2} + i \frac{3}{2}, we get z=32+i32i=32+i(321)=32+i12z = \frac{\sqrt{3}}{2} + i \frac{3}{2} - i = \frac{\sqrt{3}}{2} + i (\frac{3}{2} - 1) = \frac{\sqrt{3}}{2} + i \frac{1}{2}
step 5
To find the modulus and argument of z17z^{17}, we first find the modulus and argument of zz
step 6
The modulus of zz is z=(32)2+(12)2=34+14=1=1|z| = \sqrt{(\frac{\sqrt{3}}{2})^2 + (\frac{1}{2})^2} = \sqrt{\frac{3}{4} + \frac{1}{4}} = \sqrt{1} = 1
step 7
The argument of zz is arg(z)=tan1(1232)=tan1(13)=π6\arg(z) = \tan^{-1}(\frac{\frac{1}{2}}{\frac{\sqrt{3}}{2}}) = \tan^{-1}(\frac{1}{\sqrt{3}}) = \frac{\pi}{6}
step 8
For z17z^{17}, the modulus is z17=z17=117=1|z^{17}| = |z|^{17} = 1^{17} = 1
step 9
The argument of z17z^{17} is arg(z17)=17arg(z)=17π6=17π6\arg(z^{17}) = 17 \cdot \arg(z) = 17 \cdot \frac{\pi}{6} = \frac{17 \pi}{6}
step 10
Since the argument must be within [0,2π)[0, 2\pi), we reduce 17π6\frac{17 \pi}{6} modulo 2π2\pi: 17π62π=17π612π6=5π6\frac{17 \pi}{6} - 2\pi = \frac{17 \pi}{6} - \frac{12 \pi}{6} = \frac{5 \pi}{6}
Answer
The rectangular form of zz is 32+i12\frac{\sqrt{3}}{2} + i \frac{1}{2}. The modulus of z17z^{17} is 11, and the main argument is 5π6\frac{5 \pi}{6}.
Key Concept
Conversion between polar and rectangular forms of complex numbers
Explanation
To convert a complex number from polar to rectangular form, use Euler's formula. The modulus and argument of a complex number raised to a power can be found using properties of exponents and trigonometric identities.
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