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11th grade Complex numbers in polar form worksheet

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Complex numbers in polar form

Grade 11 Math Worksheet

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Circle the best answer, or write your answer on the line.

  1. Luz plots z = -3 + 4i. To the nearest tenth of a degree, what is its argument θ, from 0° up to 360°?

  2. Milo plots z = -5 − 12i. To the nearest tenth of a degree, what is its argument θ, from 0° up to 360°?

  3. Noah plots z = 8 − 6i. To the nearest tenth of a degree, what is its argument θ, from 0° up to 360°?

  4. Pia plots z = -15 + 8i. To the nearest tenth of a degree, what is its argument θ, from 0° up to 360°?

  5. Tala changes z = -2 + 2√3i to polar form with θ from 0° up to 360°. Which is the polar form of z?

    • 4(cos 120° + i sin 120°)
    • 4(cos 60° + i sin 60°)
    • 4(cos 240° + i sin 240°)
    • 16(cos 120° + i sin 120°)
  6. Zee changes z = -3√3 − 3i to polar form with θ from 0° up to 360°. Which is the polar form of z?

    • 6(cos 240° + i sin 240°)
    • 6(cos 30° + i sin 30°)
    • 6(cos 150° + i sin 150°)
    • 6(cos 210° + i sin 210°)
  7. Esme changes z = 5 − 5√3i to polar form with θ from 0° up to 360°. Which is the polar form of z?

    • 10(cos 150° + i sin 150°)
    • 10(cos 300° + i sin 300°)
    • 10(cos 60° + i sin 60°)
    • 100(cos 300° + i sin 300°)
  8. Jun changes z = -7 − 7i to polar form with θ from 0° up to 360°. Which is the polar form of z?

    • 7√2(cos 135° + i sin 135°)
    • 98(cos 225° + i sin 225°)
    • 7√2(cos 45° + i sin 45°)
    • 7√2(cos 225° + i sin 225°)
  9. Luz changes z = 8(cos 150° + i sin 150°) to the form a + bi. Which is z in the form a + bi?

    • -4√3 + 4i
    • 4 − 4√3i
    • 4√3 + 4i
    • -√3/2 + (1/2)i
  10. Noah changes z = 4(cos 315° + i sin 315°) to the form a + bi. Which is z in the form a + bi?

    • 2√2 + 2√2i
    • 2√2 − 2√2i
    • √2/2 − (√2/2)i
    • -2√2 + 2√2i
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11th grade Complex numbers in polar form worksheet – printable
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About this worksheet

Complex numbers in polar form. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can find the modulus r and the argument θ of a + bi in any quadrant.
  • I can write a + bi as r(cos θ + i sin θ), and back, with exact values.
  • I can read a position given in polar form as east and north parts.

Standard: N-CN.B.4 (+)

Words to know

argument θ: The angle from the positive real axis to z, turning counterclockwise.

polar form: z written as r(cos θ + i sin θ).

reference angle: The angle between z and the nearest part of the real axis.

radian: An angle unit: a full turn is 2π radians.

Common mistakes

Added the real and imaginary parts to get the distance from 0. The distance is the long side of a right triangle, so use a² + b² and a square root.

Stopped at a² + b² and gave r² instead of r.

Turned clockwise to find the angle. Angles on the complex plane turn counterclockwise from the positive real axis.

What to say

Ask: did you take the square root at the end?

Questions parents ask

What is the most common mistake with complex numbers in polar form?

Added the real and imaginary parts to get the distance from 0. The distance is the long side of a right triangle, so use a² + b² and a square root.

Are these 11th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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