Use de Moivre's Theorem to find the following. Write your answer in standard form.[2(cos 20° + i sin 20°)]3
Question
Use de Moivre's Theorem to find the following. Write your answer in standard form.[2(cos 20° + i sin 20°)]3
Solution
De Moivre's Theorem states that for any real number x and integer n, [cos(x) + i sin(x)]^n = cos(nx) + i sin(nx).
We can apply this theorem to the given problem as follows:
Given: [2(cos 20° + i sin 20°)]^3
Step 1: Apply De Moivre's Theorem = 2^3 [cos(320°) + i sin(320°)] = 8 [cos(60°) + i sin(60°)]
Step 2: Evaluate the trigonometric functions = 8 [1/2 + i * sqrt(3)/2] = 4 + 4i sqrt(3)
So, [2(cos 20° + i sin 20°)]^3 = 4 + 4i sqrt(3) in standard form.
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