Gauss plane and vector module calculation Ok guys, let's say that I have this vector: ^2}$. When I do the calculation in the first way I neglet $\operatorname{i}$, that is a part of a cathetus. If **i** is a part of a cathetus why neglet it?

If that is confusing you , you can also define the modulus $|z| $ as ;

$|z| = \sqrt{z\cdot \bar z}\qquad$$\qquad$ where $\bar z $ is the complex conjugate of $z$

let $z =a + ib$

$\bar z = a-ib$

$|z| = \sqrt{(a+ib)(a-ib)}$

$|z| = \sqrt{a^2-iab+iab-(ib)^2}$

$|z| = \sqrt{a^2-i^2\cdot b^2}$

$|z| = \sqrt{a^2+b^2}$