Magnitude of a vector (2 marks)

$\overrightarrow{AB} = \binom{-5}{12}$. Calculate the magnitude $|\overrightarrow{AB}|$.

Mark scheme (2 marks):

• M1: $\sqrt{(-5)^2 + 12^2}$ or $\sqrt{25 + 144}$
• A1: $13$ (must be exact; $\sqrt{169}$ alone scores M1A0 unless evaluated)