Answer
$13$
Work Step by Step
Let us consider that a vector $v$ is given by: $v=pi+qj$
The magnitude of a vector can be determined using the formula
$||v||=\sqrt{p^2+q^2} (1)$
We will use the formula (1) to obtain:
$||v||=\sqrt{(-5)^2+(12)^2}\\
=\sqrt{25+144}\\
=\sqrt{169}\\=13$
