TI-Nspire CX II field manual for IB Math
Modulus and argument ∣z∣, argz
Read the modulus ∣z∣ and principal argument argz of a complex number straight off the calculator (radian mode), then assemble the polar form reiθ.
Find the modulus ∣z∣ and argument argz of z=5+3i, and hence write z in the form reiθ.
Make sure the document is in Radian mode: press → 7: Settings & Status → 2: Document Settings and confirm Angle = Radian.
Compute the modulus. From the Scratchpad calculator, paste the magnitude tool: (Number) (Complex Number Tools) (Magnitude). The Nspire writes the modulus bars |▯|; inside them type → highlight i → , then for the decimal.
Compute the argument: (Polar Angle) pastes angle(. Type → i → , then . (Plain would return the exact tan−1(3/5) form.)
∣z∣≈5.83 and argz≈0.540 rad (both positive, as expected for a first-quadrant number), so z≈5.83e0.540i.
Your turn
Work each one on your calculator, then check the answer.
- 1
Find the modulus and argument of z=2+5i, and write z in the form reiθ.
- 2
Find the modulus and argument of z=−3+2i, and write z in the form reiθ.
- 3
Find the modulus and argument of z=−1−4i, and write z in the form reiθ.