Back to Topic 1.13 — Complex numbers: polar (HL only)
1.13.3Math AA HL8 flashcards

Exponential (Euler) form

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Card 1 of 81.13.3
1.13.3
Question

What is exponential (Euler) form?

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All 8 Flashcards — Exponential (Euler) form

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Card 1formula

Question

What is exponential (Euler) form?

Answer

z = r e^(iθ), with r the modulus and θ the argument in radians.

Card 2formula

Question

What is Euler's formula?

Answer

e^(iθ) = cosθ + i sinθ — it links the exponential form to the polar form.

Card 3formula

Question

How do you multiply in exponential form?

Answer

Multiply the moduli and ADD the exponents: r₁r₂ e^(i(θ₁+θ₂)) (an index law).

Card 4formula

Question

How do you divide in exponential form?

Answer

Divide the moduli and SUBTRACT the exponents: (r₁/r₂) e^(i(θ₁−θ₂)).

Card 5concept

Question

Write 4 + 4i in exponential form.

Answer

r = 4√2, θ = π/4, so 4√2 e^(iπ/4).

Card 6concept

Question

What is e^(iπ)?

Answer

−1 (so e^(iπ) + 1 = 0, Euler's identity).

Card 7concept

Question

The three forms of a complex number?

Answer

Cartesian a + bi, polar r cisθ, exponential r e^(iθ) — all the same number.

Card 8concept

Question

Why is the exponent written iθ, not θ?

Answer

Because e^(iθ) = cosθ + i sinθ; the i is essential — e^(θ) would be a real exponential.

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