SOLUTION: how do you use De Moivre's Theorem with n = 3 to express cos(3𝜃) and sin(3𝜃) in terms of cos(𝜃) and sin(𝜃)

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: how do you use De Moivre's Theorem with n = 3 to express cos(3𝜃) and sin(3𝜃) in terms of cos(𝜃) and sin(𝜃)      Log On


   

Question 1185531: how do you use De Moivre's Theorem with n = 3 to express cos(3𝜃) and sin(3𝜃) in terms of cos(𝜃) and sin(𝜃)
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
%28e%5E%28i%2Atheta%29%29%5E3+=+e%5E%283%2Ai%2Atheta%29

===> %28cos%28theta%29%2Bi%2Asin%28theta%29%29%5E3+=+cos%283%2Atheta%29%2Bi%2Asin%283%2Atheta%29
===>
===>
===>

Equate the respective real and imaginary parts from the two sides and you'll get the answer.