Try the fastest way to create flashcards
Question

Use the polar form to find each power. Write the power in rectangular form.

(3i)3(\sqrt{3}-i)^{3}

Solution

Verified
Step 1
1 of 2

Letz=r(cosθ+isinθ)z=r(\cos\theta+i\sin\theta) be the complex number in polar form, if n is positive then nth power of z i.e znz^n is given as

zn=rn(cosnθ+isinnθ)z^n=r^n(\cos n\theta+i\sin n\theta)

Here

z=3i=2(3212i)z=\sqrt{3}-i=2(\dfrac{\sqrt{3}}{2}-\dfrac{1}{2}i)

cosθ=32sinθ=12 thereforeθ=2π3\cos\theta=\dfrac{\sqrt{3}}{2} \:\:\sin \theta =-\dfrac{1}{2}\:\text{ therefore}\: \: \theta=\dfrac{2\pi}{3}

z3=(3i)3=23(cos(3..2π3)+isin(3.2π3))=8(1+0i)=8\begin{align*}z^3&=(\sqrt{3}-i)^3\\&=2^3(\cos (3..\dfrac{2\pi}{3})+i\sin( 3.\dfrac{2\pi}{3}))\\&=8(1+0i)\\&=8 \end{align*}

Rectangular form for given power of complex number is z3=8+0iz^3=8+0i

Create a free account to view solutions

Create a free account to view solutions

Recommended textbook solutions

enVision Algebra 2 1st Edition by Al Cuoco

enVision Algebra 2

1st EditionISBN: 9780328931590 (1 more)Al Cuoco
3,573 solutions
enVision Algebra 2 Common Core Student Companion 1st Edition by Al Cuoco

enVision Algebra 2 Common Core Student Companion

1st EditionISBN: 9780328931620Al Cuoco
1,212 solutions
Big Ideas Math Algebra 2: A Common Core Curriculum 1st Edition by Boswell, Larson

Big Ideas Math Algebra 2: A Common Core Curriculum

1st EditionISBN: 9781608408405 (2 more)Boswell, Larson
5,067 solutions
Big Ideas Math: Algebra 2 A Common Core Curriculum 1st Edition by Laurie Boswell, Ron Larson

Big Ideas Math: Algebra 2 A Common Core Curriculum

1st EditionISBN: 9781642088052Laurie Boswell, Ron Larson
5,066 solutions

More related questions

1/4

1/7