Consider the complex number z=−23+2i.What is z3 ?Hint: z has a modulus of 4 and an argument of 150∘.Choose 1 answer:(A) −6−10.4i(B) 64i(C) −10.4+6i(D) −32−55.4i
Q. Consider the complex number z=−23+2i.What is z3 ?Hint: z has a modulus of 4 and an argument of 150∘.Choose 1 answer:(A) −6−10.4i(B) 64i(C) −10.4+6i(D) −32−55.4i
Given complex number: We are given the complex number z=−23+2i. We are also given that z has a modulus of 4 and an argument of 150 degrees. To find z3, we can use De Moivre's Theorem, which states that (r(cos(θ)+isin(θ)))n=rn(cos(nθ)+isin(nθ)), where r is the modulus and θ is the argument of the complex number.
Convert to radians: First, we convert the argument of 150 degrees to radians because trigonometric functions in the complex plane are typically expressed in radians. 150 degrees is equivalent to 150×(π/180)=65π radians.
Apply De Moivre's Theorem: Now we can apply De Moivre's Theorem. We have r=4 and θ=65π. We want to find z3, so we raise the modulus to the power of 3 and multiply the argument by 3.r3=43=64θ×3=65π×3=25π
Simplify argument: Using De Moivre's Theorem, we get: z3=64×(cos(25π)+isin(25π))Since the sine and cosine functions are periodic with a period of 2π, we can simplify the argument 25π to 2π by subtracting 2π (which is one full period) from 25π.25π−2π=2π
Find cosine and sine: Now we can find the cosine and sine of π/2: cos(π/2)=0sin(π/2)=1So, z3=64×(0+i×1)=64i