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10.5: Fomu ya Polar ya Hesabu Complex

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    178408
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    Malengo ya kujifunza
    • Panda namba tata katika ndege tata.
    • Pata thamani kamili ya idadi tata.
    • Andika namba tata katika fomu ya polar.
    • Badilisha namba tata kutoka polar hadi fomu ya mstatili.
    • Pata bidhaa za namba tata katika fomu ya polar.
    • Pata quotients ya idadi tata katika fomu ya polar.
    • Pata nguvu za idadi tata katika fomu ya polar.
    • Pata mizizi ya namba tata katika fomu ya polar.

    “Mungu aliumba integers; yote ni kazi ya mwanadamu.” Nukuu hii maarufu sana na mwanahisabati wa Kijerumani wa karne ya kumi na tisa Leopold Kronecker huweka hatua kwa sehemu hii kwenye fomu ya polar ya namba tata. Idadi tata zuliwa na watu na kuwakilisha zaidi ya miaka elfu ya uchunguzi wa kuendelea na mapambano na wanahisabati kama vile Pythagoras, Descartes, De Moivre, Euler, Gauss, na wengine. Nambari tata zilijibu maswali ambayo kwa karne nyingi zilikuwa zimeshangaa akili kubwa zaidi katika sayansi.

    Sisi kwanza tulikutana na idadi tata katika sehemu ya Hesabu Complex. Katika sehemu hii, tutazingatia mechanics ya kufanya kazi na namba tata: tafsiri ya namba tata kutoka kwa fomu ya polar hadi fomu ya mstatili na kinyume chake, tafsiri ya idadi tata katika mpango wa maombi, na matumizi ya Theorem ya De Moivre.

    Kupanga Nambari Complex katika Ndege Complex

    Kupanga namba tata\(a+bi\) ni sawa na kupanga namba halisi, isipokuwa kwamba mhimili usio na usawa unawakilisha sehemu halisi ya namba\(a\), na mhimili wima unawakilisha sehemu ya kufikiri ya namba,\(bi\).

    Jinsi ya: Kutokana na idadi tata\(a+bi\), plot it in the complex plane.
    1. Weka mhimili usio na usawa kama mhimili halisi na mhimili wima kama mhimili wa kufikiri.
    2. Panda hatua katika ndege ngumu kwa kusonga\(a\) vitengo katika mwelekeo usio na usawa na\(b\) vitengo katika mwelekeo wa wima.
    Mfano\(\PageIndex{1}\): Plotting a Complex Number in the Complex Plane

    Panda idadi tata\(2−3i\) katika ndege tata.

    Suluhisho

    Kutoka asili, fanya vitengo viwili katika mwelekeo mzuri wa usawa na vitengo vitatu katika mwelekeo mbaya wa wima. Angalia Kielelezo\(\PageIndex{1}\).

    Mpango wa 2-3i katika ndege ngumu (2 pamoja na mhimili halisi, -3 pamoja na mhimili wa kufikiri).
    Kielelezo\(\PageIndex{1}\)
    Zoezi\(\PageIndex{1}\)

    Panda hatua\(1+5i\) katika ndege tata.

    Jibu
    Mpango wa 1+5i katika ndege ngumu (1 pamoja na mhimili halisi, 5 pamoja na mhimili wa kufikiri).
    Kielelezo\(\PageIndex{2}\)

    Kutafuta Thamani kamili ya Idadi Tata

    Hatua ya kwanza kuelekea kufanya kazi na idadi tata katika fomu ya polar ni kupata thamani kamili. Thamani kamili ya idadi tata ni sawa na ukubwa wake, au\(| z |\). Inapima umbali kutoka asili hadi hatua katika ndege. Kwa mfano, grafu ya\(z=2+4i\), katika Kielelezo\(\PageIndex{3}\), inaonyesha\(| z |\).

    Mpango ya 2+4i katika ndege tata na ukubwa wake, |z| = rad 20.
    Kielelezo\(\PageIndex{3}\)
    THAMANI KAMILI YA IDADI TATA

    Kutokana\(z=x+yi\), idadi tata, thamani kamili ya\(z\) hufafanuliwa kama

    \[| z |=\sqrt{x^2+y^2}\]

    Ni umbali kutoka asili hadi hatua\((x,y)\).

    Kumbuka kwamba thamani kamili ya idadi halisi inatoa umbali wa idadi kutoka\(0\), wakati thamani kamili ya idadi tata inatoa umbali wa idadi kutoka asili,\((0, 0)\).

    Mfano\(\PageIndex{2}\): Finding the Absolute Value of a Complex Number with a Radical

    Kupata thamani kamili ya\(z=\sqrt{5}−i\).

    Suluhisho

    Kutumia formula, tuna

    \[\begin{align*} |z| &= \sqrt{x^2+y^2} \\ |z| &= \sqrt{{(\sqrt{5})}^2+{(-1)}^2} \\ |z| &= \sqrt{5+1} \\ |z| &= \sqrt{6} \end{align*}\]

    Angalia Kielelezo\(\PageIndex{4}\).

    Plot ya z= (rad5 - i) katika ndege tata na ukubwa wake rad6.
    Kielelezo\(\PageIndex{4}\)
    Zoezi\(\PageIndex{2}\)

    Pata thamani kamili ya idadi tata\(z=12−5i\).

    Jibu

    \(13\)

    Mfano\(\PageIndex{3}\): Finding the Absolute Value of a Complex Number

    Kutokana\(z=3−4i\), tafuta\(| z |\).

    Suluhisho

    Kutumia formula, tuna

    \[\begin{align*} | z | &= \sqrt{x^2+y^2} \\ | z | &= \sqrt{{(3)}^2+{(-4)}^2} \\ | z | &= \sqrt{9+16} \\ | z | &= \sqrt{25} \\ | z | &= 5 \end{align*}\]

    Thamani kamili\(z\) ni\(5\). Angalia Kielelezo\(\PageIndex{5}\).

    Mpango wa (3-4i) katika ndege tata na ukubwa wake |z| =5.
    Kielelezo\(\PageIndex{5}\)
    Zoezi\(\PageIndex{3}\)

    Kutokana\(z=1−7i\), tafuta\(| z |\).

    Jibu

    \(| z |=\sqrt{50}=5\sqrt{2}\)

    Kuandika Hesabu Complex katika Fomu ya Polar

    Fomu ya polar ya nambari tata inaonyesha idadi kwa suala la angle\(\theta\) na umbali wake kutoka kwa asili\(r\). Kutokana na idadi tata katika fomu mstatili walionyesha kama\(z=x+yi\), tunatumia formula sawa uongofu kama sisi kufanya kuandika idadi katika fomu trigonometric:

    \[\begin{align*} x &= r \cos \theta \\ y &= r \sin \theta \\ r &= \sqrt{x^2+y^2} \end{align*}\]

    Sisi kupitia mahusiano haya katika Kielelezo\(\PageIndex{6}\).

    Triangle iliyopangwa katika ndege ngumu (x mhimili ni halisi, y axis ni imaginary). Msingi ni pamoja na mhimili x/halisi, urefu ni baadhi y/thamani imaginary katika Q 1, na hypotenuse r inaenea kutoka asili hadi hatua hiyo (x+yi) katika Q 1. Pembe katika asili ni theta. Kuna arc kupitia (x+yi).
    Kielelezo\(\PageIndex{6}\)

    Tunatumia moduli ya neno kuwakilisha thamani kamili ya nambari tata, au umbali kutoka kwa asili hadi hatua\((x,y)\). Moduli, basi, ni sawa na\(r\), radius katika fomu ya polar. Tunatumia\(\theta\) kuonyesha angle ya mwelekeo (kama vile kuratibu polar). Kubadilisha, tuna

    \[\begin{align*} z &= x+yi \\ z &= r \cos \theta+(r \sin \theta)i \\ z &= r(\cos \theta+i \sin \theta) \end{align*}\]

    AINA YA POLAR YA IDADI TATA

    Kuandika namba tata katika fomu ya polar inahusisha kanuni zifuatazo za uongofu:

    \[\begin{align} x &= r \cos \theta \\ y &= r \sin \theta \\ r &= \sqrt{x^2+y^2} \end{align}\]

    Kufanya badala ya moja kwa moja, tuna

    \[\begin{align} z &= x+yi \\ z &= (r \cos \theta)+i(r \sin \theta) \\ z &= r(\cos \theta+i \sin \theta) \end{align}\]

    \(r\)wapi moduli na\(\theta\) ni hoja. Mara nyingi tunatumia kifupi\(r\; cis \theta\) kuwakilisha\(r(\cos \theta+i \sin \theta)\).

    Mfano\(\PageIndex{4}\): Expressing a Complex Number Using Polar Coordinates

    Eleza nambari tata\(4i\) kwa kutumia kuratibu za polar.

    Suluhisho

    Katika ndege ngumu, idadi hiyo\(z=4i\) ni sawa na\(z=0+4i\). Kuandika kwa fomu ya polar, tunapaswa kuhesabu\(r\) kwanza.

    \[\begin{align*} r &= \sqrt{x^2+y^2} \\ r &= \sqrt{0^2+4^2} \\ r &= \sqrt{16} \\ r &= 4 \end{align*}\]

    Kisha, tunaangalia\(x\). Ikiwa\(x=r \cos \theta\), na\(x=0\), basi\(\theta=\dfrac{\pi}{2}\). Katika kuratibu polar, idadi tata\(z=0+4i\) inaweza kuandikwa kama\(z=4\left(\cos\left(\dfrac{\pi}{2}\right)+i \sin\left(\dfrac{\pi}{2}\right)\right) \text{ or } 4\; cis\left( \dfrac{\pi}{2}\right)\). Angalia Kielelezo\(\PageIndex{7}\).

    Plot ya z=4i katika ndege tata, pia inaonyesha kwamba katika polar kuratibu itakuwa (4, pi/2).
    Kielelezo\(\PageIndex{7}\)
    Zoezi\(\PageIndex{4}\)

    Eleza\(z=3i\) kama\(r\space cis \theta\) katika fomu ya polar.

    Jibu

    \(z=3\left(\cos\left(\dfrac{\pi}{2}\right)+i \sin\left(\dfrac{\pi}{2}\right)\right)\)

    Mfano\(\PageIndex{5}\): Finding the Polar Form of a Complex Number

    Kupata aina polar ya\(−4+4i\).

    Suluhisho

    Kwanza, kupata thamani ya\(r\).

    \[\begin{align*} r &= \sqrt{x^2+y^2} \\ r &= \sqrt{{(−4)}^2+(4^2)} \\ r &= \sqrt{32} \\ r &= 4\sqrt{2} \end{align*}\]

    Pata angle\(\theta\) kwa kutumia formula:

    \[\begin{align*} \cos \theta &= \dfrac{x}{r} \\ \cos \theta &= \dfrac{−4}{4\sqrt{2}} \\ \cos \theta &= −\dfrac{1}{\sqrt{2}} \\ \theta &= {\cos}^{−1} \left(−\dfrac{1}{\sqrt{2}}\right)\\ &= \dfrac{3\pi}{4} \end{align*}\]

    Hivyo, suluhisho ni\(4\sqrt{2}\space cis \left(\dfrac{3\pi}{4}\right)\).

    Zoezi\(\PageIndex{5}\)

    Andika\(z=\sqrt{3}+i\) kwa fomu ya polar.

    Jibu

    \(z=2\left(\cos\left(\dfrac{\pi}{6}\right)+i \sin\left(\dfrac{\pi}{6}\right)\right)\)

    Kubadilisha Idadi Complex kutoka Polar hadi Fomu ya Rectangular

    Kubadili namba tata kutoka fomu ya polar hadi fomu ya mstatili ni suala la kutathmini kile kinachopewa na kutumia mali ya usambazaji. Kwa maneno mengine, kutokana\(z=r(\cos \theta+i \sin \theta)\), kwanza tathmini kazi za trigonometric\(\cos \theta\) na\(\sin \theta\). Kisha, kuzidisha kupitia\(r\).

    Mfano\(\PageIndex{6A}\): Converting from Polar to Rectangular Form

    Badilisha fomu ya polar ya nambari tata iliyotolewa kwa fomu ya mstatili:

    \(z=12\left(\cos\left(\dfrac{\pi}{6}\right)+i \sin\left(\dfrac{\pi}{6}\right)\right)\)

    Suluhisho

    Tunaanza kwa kutathmini maneno ya trigonometric.

    \[\begin{align*} \cos\left(\dfrac{\pi}{6}\right)&= \dfrac{\sqrt{3}}{2} \text{ and } \sin(\dfrac{\pi}{6})=\dfrac{1}{2}\\ \text {After substitution, the complex number is}\\ z&= 12\left(\dfrac{\sqrt{3}}{2}+\dfrac{1}{2}i\right) \end{align*}\]

    Tunatumia mali ya usambazaji:

    \[\begin{align*} z &= 12\left(\dfrac{\sqrt{3}}{2}+\dfrac{1}{2}i\right) \\ &= (12)\dfrac{\sqrt{3}}{2}+(12)\dfrac{1}{2}i \\ &= 6\sqrt{3}+6i \end{align*}\]

    Fomu ya mstatili wa hatua iliyotolewa katika fomu ngumu ni\(6\sqrt{3}+6i\).

    Mfano\(\PageIndex{6B}\): Finding the Rectangular Form of a Complex Number

    Pata fomu ya mstatili wa nambari tata iliyotolewa\(r=13\) na\(\tan \theta=\dfrac{5}{12}\).

    Suluhisho

    Kama\(\tan \theta=\dfrac{5}{12}\), na\(\tan \theta=\dfrac{y}{x}\), sisi kwanza kuamua\(r=\sqrt{x^2+y^2}=\sqrt{122+52}=13\). Sisi kisha kupata\(\cos \theta=\dfrac{x}{r}\) na\(\sin \theta=\dfrac{y}{r}\).

    \[\begin{align*} z &= 13\left(\cos \theta+i \sin \theta\right) \\ &= 13\left(\dfrac{12}{13}+\dfrac{5}{13}i\right) \\ &=12+5i \end{align*}\]

    Fomu ya mstatili wa nambari iliyotolewa katika fomu ngumu ni\(12+5i\).

    Zoezi\(\PageIndex{6}\)

    Badilisha nambari tata kwa fomu ya mstatili:

    \(z=4\left(\cos \dfrac{11\pi}{6}+i \sin \dfrac{11\pi}{6}\right)\)

    Jibu

    \(z=2\sqrt{3}−2i\)

    Kutafuta Bidhaa za Hesabu Complex katika Fomu ya Polar

    Sasa kwa kuwa tunaweza kubadilisha namba tata kwa fomu ya polar tutajifunza jinsi ya kufanya shughuli kwa idadi tata katika fomu ya polar. Kwa sehemu hii yote, tutafanya kazi na fomu zilizotengenezwa na mtaalamu wa hisabati wa Kifaransa Abraham de Moivre (1667-1754). Njia hizi zimefanya kufanya kazi na bidhaa, quotients, nguvu, na mizizi ya namba tata rahisi zaidi kuliko zinaonekana. Sheria zinategemea kuzidisha moduli na kuongeza hoja.

    BIDHAA ZA IDADI TATA KATIKA FOMU YA POLAR

    Ikiwa\(z_1=r_1(\cos \theta_1+i \sin \theta_1)\) na\(z_2=r_2(\cos \theta_2+i \sin \theta_2)\), basi bidhaa za namba hizi hutolewa kama:

    \[\begin{align} z_1z_2 &= r_1r_2[ \cos(\theta_1+\theta_2)+i \sin(\theta_1+\theta_2) ] \\ z_1z_2 &= r_1r_2\space cis(\theta_1+\theta_2) \end{align}\]

    Angalia kwamba bidhaa zinaita kuzidisha moduli na kuongeza pembe.

    Mfano\(\PageIndex{7}\): Finding the Product of Two Complex Numbers in Polar Form

    Kupata bidhaa ya\(z_1z_2\), kutokana\(z_1=4(\cos(80°)+i \sin(80°))\) na\(z_2=2(\cos(145°)+i \sin(145°))\).

    Suluhisho

    Fuata formula

    \[\begin{align*} z_1z_2 &= 4⋅2[\cos(80°+145°)+i \sin(80°+145°)] \\ z_1z_2 &= 8[\cos(225°)+i \sin(225°)] \\ z_1z_2 &= 8\left[\cos\left(\dfrac{5\pi}{4}\right)+i \sin\left(\dfrac{5\pi}{4}\right) \right] \\ z_1z_2 &= 8\left[−\dfrac{\sqrt{2}}{2}+i\left(−\dfrac{\sqrt{2}}{2}\right) \right] \\ z_1z_2 &= −4\sqrt{2}−4i\sqrt{2} \end{align*}\]

    Kutafuta Quotients ya Hesabu Complex katika Fomu Polar

    Kiwango cha namba mbili ngumu katika fomu ya polar ni quotient ya moduli mbili na tofauti ya hoja mbili.

    QUOTIENTS YA IDADI TATA KATIKA FOMU YA POLAR

    Ikiwa\(z_1=r_1(\cos \theta_1+i \sin \theta_1)\) na\(z_2=r_2(\cos \theta_2+i \sin \theta_2)\), basi quotient ya namba hizi ni

    \[\dfrac{z_1}{z_2}=\dfrac{r_1}{r_2}[\cos(\theta_1−\theta_2)+i \sin(\theta_1−\theta_2) ],\space z_2≠0\]

    \[\dfrac{z_1}{z_2}=\dfrac{r_1}{r_2}\space cis(\theta_1−\theta_2),\space z_2≠0\]

    Angalia kwamba moduli imegawanywa, na pembe zinaondolewa.

    Jinsi ya: Kutokana na namba mbili ngumu katika fomu ya polar, pata quotient
    1. Gawanya\(\dfrac{r_1}{r_2}\).
    2. Kupata\(\theta_1−\theta_2\).
    3. Badilisha matokeo katika formula:\(z=r(\cos \theta+i \sin \theta)\). Kuchukua nafasi\(r\) na\(\dfrac{r_1}{r_2}\), na kuchukua nafasi\(\theta\) na\(\theta_1−\theta_2\).
    4. Tumia maneno mapya ya trigonometric na uongeze kupitia\(r\).
    Mfano\(\PageIndex{8}\): Finding the Quotient of Two Complex Numbers

    Kupata quotient ya\(z_1=2(\cos(213°)+i \sin(213°))\) na\(z_2=4(\cos(33°)+i \sin(33°))\).

    Suluhisho

    Kutumia formula, tuna

    \[\begin{align*} \dfrac{z_1}{z_2} &= \dfrac{2}{4}[\cos(213°−33°)+i \sin(213°−33°)] \\ \dfrac{z_1}{z_2} &= \dfrac{1}{2}[\cos(180°)+i \sin(180°)] \\ \dfrac{z_1}{z_2} &= \dfrac{1}{2}[−1+0i] \\ \dfrac{z_1}{z_2} &= −\dfrac{1}{2}+0i \\ \dfrac{z_1}{z_2} &= −\dfrac{1}{2} \end{align*}\]

    Zoezi\(\PageIndex{8}\)

    Kupata bidhaa na quotient ya\(z_1=2\sqrt{3}(\cos(150°)+i \sin(150°))\) na\(z_2=2(\cos(30°)+i \sin(30°))\).

    Jibu

    \(z_1z_2=−4\sqrt{3}\);\(\dfrac{z_1}{z_2}=−\dfrac{\sqrt{3}}{2}+\dfrac{3}{2}i\)

    Kupata Nguvu za Hesabu Complex katika Fomu ya Polar

    Kupata nguvu za namba tata ni rahisi sana kwa kutumia Theorem ya De Moivre. Inasema kwamba, kwa integer chanya\(n\),\(z^n\) hupatikana kwa kuongeza moduli kwa\(n^{th}\) nguvu na kuzidisha hoja na\(n\). Ni njia ya kawaida inayotumiwa katika hisabati ya kisasa.

    THEOREM YA DE MOIVRE

    Ikiwa\(z=r(\cos \theta+i \sin \theta)\) ni idadi tata, basi

    \[\begin{align} z^n &= r^n[\cos(n\theta)+i \sin(n\theta) ] \\ z^n &= r^n\space cis(n\theta) \end{align}\]

    ambapo\(n\) ni integer chanya.

    Mfano\(\PageIndex{9}\): Evaluating an Expression Using De Moivre’s Theorem

    Tathmini maneno kwa\({(1+i)}^5\) kutumia Theorem ya De Moivre.

    Suluhisho

    Kwa kuwa Theorem ya De Moivre inatumika kwa namba tata zilizoandikwa katika fomu ya polar, lazima kwanza tuandike\((1+i)\) kwa fomu ya polar. Hebu kupata\(r\).

    \[\begin{align*} r &= \sqrt{x^2+y^2} \\ r &= \sqrt{{(1)}^2+{(1)}^2} \\ r &= \sqrt{2} \end{align*}\]

    Kisha sisi kupata\(\theta\). Kutumia formula\(\tan \theta=\dfrac{y}{x}\) inatoa

    \[\begin{align*} \tan \theta &= \dfrac{1}{1} \\ \tan \theta &= 1 \\ \theta &= \dfrac{\pi}{4} \end{align*}\]

    Tumia Theorem ya De Moivre ili kutathmini usemi.

    \[\begin{align*} {(a+bi)}^n &= r^n[\cos(n\theta)+i \sin(n\theta)] \\ {(1+i)}^5 &= {(\sqrt{2})}^5\left[ \cos\left(5⋅\dfrac{\pi}{4}\right)+i \sin\left(5⋅\dfrac{\pi}{4}\right) \right] \\ {(1+i)}^5 &= 4\sqrt{2}\left[ \cos\left(\dfrac{5\pi}{4}\right)+i \sin\left(\dfrac{5\pi}{4}\right) \right] \\ {(1+i)}^5 &= 4\sqrt{2}\left[ −\dfrac{\sqrt{2}}{2}+i\left(−\dfrac{\sqrt{2}}{2}\right) \right] \\ {(1+i)}^5 &= −4−4i \end{align*}\]

    Kutafuta Mizizi ya Hesabu Complex katika Fomu ya Polar

    Ili kupata\(n^{th}\) mzizi wa idadi tata katika fomu ya polar, tunatumia Theorem ya\(n^{th}\) Mizizi au Theorem ya De Moivre na kuongeza idadi tata kwa nguvu na kielelezo cha busara. Kuna njia kadhaa za kuwakilisha formula ya kutafuta\(n^{th}\) mizizi ya namba tata katika fomu ya polar.

    YA\(N^{TH}\) ROOT THEOREM

    Ili kupata\(n^{th}\) mizizi ya namba tata katika fomu ya polar, tumia fomu iliyotolewa kama

    \[z^{\tfrac{1}{n}}=r^{\tfrac{1}{n}}\left[ \cos\left(\dfrac{\theta}{n}+\dfrac{2k\pi}{n}\right)+i \sin\left(\dfrac{\theta}{n}+\dfrac{2k\pi}{n}\right) \right]\]

    wapi\(k=0, 1, 2, 3, . . . , n−1\). Tunaongeza\(\dfrac{2k\pi}{n}\)\(\dfrac{\theta}{n}\) ili kupata mizizi ya mara kwa mara.

    Mizizi ya Idadi Tata

    Kutathmini mizizi mchemraba wa\(z=8\left(\cos\left(\frac{2\pi}{3}\right)+i\sin\left(\frac{2\pi}{3}\right)\right)\).

    Suluhisho

    Tuna

    \[\begin{align*} z^{\frac{1}{3}} &= 8^{\frac{1}{3}}\left[ \cos\left(\frac{\frac{2\pi}{3}}{3}+\frac{2k\pi}{3}\right)+i \sin\left(\frac{\frac{2\pi}{3}}{3}+\frac{2k\pi}{3}\right) \right] \\ z^{\frac{1}{3}} &= 2\left[ \cos\left(\frac{2\pi}{9}+\frac{2k\pi}{3}\right)+i \sin\left(\frac{2\pi}{9}+\frac{2k\pi}{3}\right) \right] \end{align*}\]

    Kutakuwa na mizizi mitatu:\(k=0, 1, 2\). Wakati\(k=0\), tuna

    \(z^{\frac{1}{3}}=2\left(\cos\left(\dfrac{2\pi}{9}\right)+i \sin\left(\dfrac{2\pi}{9}\right)\right)\)

    Wakati\(k=1\), tuna

    \[\begin{align*} z^{\frac{1}{3}} &=2\left[ \cos\left(\dfrac{2\pi}{9}+\dfrac{6\pi}{9}\right)+i \sin\left(\dfrac{2\pi}{9}+\dfrac{6\pi}{9}\right) \right] \;\;\;\;\;\;\;\;\; \text{Add }\dfrac{2(1)\pi}{3} \text{ to each angle.} \\ z^{\frac{1}{3}} &= 2\left(\cos\left(\dfrac{8\pi}{9}\right)+i \sin\left(\dfrac{8\pi}{9}\right)\right) \end{align*}\]

    Wakati\(k=2\), tuna

    \[\begin{align*} z^{\frac{1}{3}} &= 2\left[ \cos\left(\dfrac{2\pi}{9}+\dfrac{12\pi}{9}\right)+i \sin\left(\dfrac{2\pi}{9}+\dfrac{12\pi}{9}\right) \right] \;\;\;\;\;\;\; \text{Add }\dfrac{2(2)\pi}{3} \text{ to each angle.} \\ z^{\frac{1}{3}} &= 2\left(\cos\left(\dfrac{14\pi}{9}\right)+i \sin\left(\dfrac{14\pi}{9}\right)\right) \end{align*}\]

    Kumbuka kupata denominator ya kawaida ili kurahisisha sehemu ndogo katika hali kama hii. Kwa\(k=1\), kurahisisha angle ni

    \[\begin{align*} \dfrac{\dfrac{2\pi}{3}}{3}+\dfrac{2(1)\pi}{3} &= \dfrac{2\pi}{3}(\dfrac{1}{3})+\dfrac{2(1)\pi}{3}\left(\dfrac{3}{3}\right) \\ &=\dfrac{2\pi}{9}+\dfrac{6\pi}{9} \\ &=\dfrac{8\pi}{9} \end{align*}\]

    Zoezi\(\PageIndex{10}\)

    Kupata nne mizizi ya nne ya\(16(\cos(120°)+i \sin(120°))\).

    Jibu

    \(z_0=2(\cos(30°)+i \sin(30°))\)

    \(z_1=2(\cos(120°)+i \sin(120°))\)

    \(z_2=2(\cos(210°)+i \sin(210°))\)

    \(z_3=2(\cos(300°)+i \sin(300°))\)

    Media

    Fikia rasilimali hizi za mtandaoni kwa maelekezo ya ziada na mazoezi na aina za polar za namba tata.

    • Bidhaa na Quotient ya Hesabu Complex katika Fomu ya Trigonometric
    • Theorem ya De Moivre

    Dhana muhimu

    • Nambari tata katika fomu\(a+bi\) zimepangwa katika ndege ngumu sawa na njia za kuratibu za mstatili zinapangwa katika ndege ya mstatili. Lebo\(x\) -axis kama mhimili halisi na\(y\) - mhimili kama mhimili wa kufikiri. Angalia Mfano\(\PageIndex{1}\).
    • Thamani kamili ya idadi tata ni sawa na ukubwa wake. Ni umbali kutoka asili hadi hatua:\(| z |=\sqrt{a^2+b^2}\). Angalia Mfano\(\PageIndex{2}\) na Mfano\(\PageIndex{3}\).
    • Kuandika namba tata katika fomu ya polar, tunatumia formula\(x=r \cos \theta\)\(y=r \sin \theta\), na\(r=\sqrt{x^2+y^2}\). Kisha,\(z=r(\cos \theta+i \sin \theta)\). Angalia Mfano\(\PageIndex{4}\) na Mfano\(\PageIndex{5}\).
    • Ili kubadilisha kutoka fomu ya polar hadi fomu ya mstatili, kwanza tathmini kazi za trigonometric. Kisha, kuzidisha kupitia\(r\). Angalia Mfano\(\PageIndex{6}\) na Mfano\(\PageIndex{7}\).
    • Ili kupata bidhaa ya namba mbili ngumu, kuzidisha moduli mbili na kuongeza pembe mbili. Tathmini kazi za trigonometric, na uongeze kutumia mali ya usambazaji. Angalia Mfano\(\PageIndex{8}\).
    • Ili kupata quotient ya namba mbili ngumu katika fomu ya polar, pata quotient ya moduli mbili na tofauti ya pembe mbili. Angalia Mfano\(\PageIndex{9}\).
    • Ili kupata nguvu ya nambari tata\(z^n\), ongeza\(r\) kwa nguvu\(n\), na uongeze\(\theta\) na\(n\). Angalia Mfano\(\PageIndex{10}\).
    • Kupata mizizi ya idadi tata ni sawa na kuongeza idadi tata kwa nguvu, lakini kwa kutumia exponent busara. Angalia Mfano\(\PageIndex{11}\).