modulus

A complex number \( z \) is a number of the form \( z = a + bi \), where \( a \) and \( b \) are any real numbers. The set of complex numbers is denoted by \( \mathbb{C} \).

Besides the familiar algebraic form, complex numbers can also be expressed in polar form as:

\[
z = r (\cos\theta + i\sin\theta)
\]