MediumPolar form

Gilbert Strang, Calculus, 3rd edition (Wellesley-Cambridge Press; MIT OpenCourseWare RES.18-001) §9.4 Complex Numbers, #16 · Complex Numbers · Polar form

Multiply out …, to find the real part … and the imaginary…

Multiply out $(cos θ + i sin θ)^{3} = e^{3 i θ}$ , to find the real part $cos 3 θ$ and the imaginary part $sin 3 θ$ in terms of $cos θ$ and $sin θ$ .

~8 minWritten answer · check your work with Lemma

Gilbert Strang, Calculus, 3rd edition (Wellesley-Cambridge Press; MIT OpenCourseWare RES.18-001) · §9.4 Complex Numbers, #16

Stuck? A gentle nudge

No hints for this one.

Something off?

Workspace

Your working

Check your full solution

Upload photos of your handwritten work or a PDF, and Lemma will read it and tell you whether it's right — and where it first goes wrong if not.