# Modulus and argument of complex number

**Modulus and argument of complex number (Question)**

- Determine the modulus and argument of 10 + 5i.
- Express 10 + 5i in the form of r(cos a + sin a*i)

*Guide:
*

|a + bi| = r = √(a^{2} + b^{2})

Argument of the complex number = tan^{-1}(b/a)

Argument form of a complex number

x + yi = r(cos a + sin a*i)

**Modulus and argument of complex number (Answer)**

- Modulus = √125, Argument = 0.464rad
- 10 + 5i = √125(cos 0.464rad + sin0.464rad*i)

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