- #1

DryRun

Gold Member

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## Homework Statement

I could not type it here, so i made a screenshot and posted it below.

## Homework Equations

it's about complex numbers undergraduate level. i'm currently doing Euler's formula and De Moivre's theorem, although i'm not sure that the solution lies there.

## The Attempt at a Solution

i tried doing it by adding the values inside the cos() but when verifying via calculator with a dummy data, it didn't add up.