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Consider the complex number 
z=-3sqrt3-3i.
What is 
z^(3) ?
Hint: 
z has a modulus of 6 and an argument of 
210^(@).
Choose 1 answer:
(A) 
-216 i
(B) -216
(c) 
-108+187.1 i
(D) 
108+187.1 i

Consider the complex number z=333i z=-3 \sqrt{3}-3 i .\newlineWhat is z3 z^{3} ?\newlineHint: z z has a modulus of 66 and an argument of 210 210^{\circ} .\newlineChoose 11 answer:\newline(A) 216i -216 i \newline(B) 216-216\newline(C) 108+187.1i -108+187.1 i \newline(D) 108+187.1i 108+187.1 i

Full solution

Q. Consider the complex number z=333i z=-3 \sqrt{3}-3 i .\newlineWhat is z3 z^{3} ?\newlineHint: z z has a modulus of 66 and an argument of 210 210^{\circ} .\newlineChoose 11 answer:\newline(A) 216i -216 i \newline(B) 216-216\newline(C) 108+187.1i -108+187.1 i \newline(D) 108+187.1i 108+187.1 i
  1. Identify modulus and argument: Identify the modulus and argument of the complex number zz. Given z=333iz = -3\sqrt{3} - 3i, we are told that the modulus of zz is 66 and the argument is 210210 degrees. This information will be used to find z3z^{3} using the polar form of the complex number.
  2. Convert to polar form: Convert the complex number zz to its polar form. The polar form of a complex number is given by z=r(cos(θ)+isin(θ))z = r(\cos(\theta) + i\sin(\theta)), where rr is the modulus and θ\theta is the argument. For zz, we have r=6r = 6 and θ=210\theta = 210 degrees. Therefore, the polar form of zz is z=6(cos(210°)+isin(210°))z = 6(\cos(210°) + i\sin(210°)).
  3. Use De Moivre's Theorem: Use De Moivre's Theorem to find z3z^{3}. De Moivre's Theorem states that (r(cos(θ)+isin(θ)))n=rn(cos(nθ)+isin(nθ))(r(\cos(\theta) + i\sin(\theta)))^{n} = r^{n}(\cos(n\theta) + i\sin(n\theta)). We want to find z3z^{3}, so we will raise the polar form of zz to the power of 33.
  4. Calculate z3z^{3}: Calculate z3z^{3} using De Moivre's Theorem.\newlineWe have z3=(6(cos(210°)+isin(210°)))3=63(cos(3210°)+isin(3210°))=216(cos(630°)+isin(630°))z^{3} = (6(\cos(210°) + i\sin(210°)))^{3} = 6^{3}(\cos(3\cdot210°) + i\sin(3\cdot210°)) = 216(\cos(630°) + i\sin(630°)).
  5. Simplify trigonometric functions: Simplify the trigonometric functions.\newlineSince 630°630° is equivalent to 270°270° (as 630°360°=270°630° - 360° = 270°), we can simplify the expression to 216(cos(270°)+isin(270°))216(\cos(270°) + i\sin(270°)). The cosine of 270°270° is 00, and the sine of 270°270° is 1-1. Therefore, z3=216(0i)=216iz^{3} = 216(0 - i) = -216i.

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