Why does pi appear in Euler's formula?
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Answer: Complex exponentials describe rotation
Complex exponentials describe rotation ✓ — Correct! In the complex plane, e^(ix) traces rotation. Angles in rotation are measured in radians, and radians naturally use pi because a half-turn is π.
Euler defined pi there — Wrong. Euler did not invent pi inside this formula. The formula works because complex exponentials connect naturally to circular rotation.
Pi fixes negative numbers — Wrong. Pi is not there to repair negative numbers. It appears because the formula is fundamentally about angle and rotation.