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### Course: Precalculus>Unit 3

Lesson 5: Modulus (absolute value) and argument (angle) of complex numbers

# Complex numbers with the same modulus (absolute value)

Sal shows how to determine which members in a set of complex numbers have the same modulus (or absolute value). He also shows how to visualize all of the complex numbers with a given modulus as a circle centered at the origin on the complex plane, since all points on such a circle are the same distance from the origin. Created by Sal Khan.

## Want to join the conversation?

• Hi!
So, one of the questions said to find the modulus of 4 - i. My answer was sqrt of 15 because I did (4)^2 + (-i)^2 = 16 + -1 = 15. And then I put it under a radical. However, the correct answer was 17. Why is that? Was I just supposed to do (4 - i)^2 and then sqrt it?