NUM007 · Numbers & number systems · Classes 11–12
Complex Numbers
Numbers z = a + bi with i² = −1, drawn as points on the Argand plane.
Complex Numbers📐 Formula
|z| = √(a² + b²); arg z = atan2(b, a); z̄ = a − bi
✏️ Worked example
z = 3 + 4i: |z| = 5, arg ≈ 53.13°.
🌍 Where it is used
Electrical engineering (AC circuits) and signal processing.
❓ Quick check
i² =