Triangle Inequality for Complex Numbers (|z₁ + z₂| ≤ |z₁| + |z₂|)

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|z₁ + z₂| ≤ |z₁| + |z₂|

What each symbol means

SymbolWhat it stands for
EqualityHolds with equality iff z₁, z₂ have same argument (same direction from origin)
z_1, z_2Any two complex numbers

When to use this

True for all z₁, z₂ ∈ ℂ. Geometrically: one side of triangle ≤ sum of other two sides in Argand plane.