The unit vector n^=r⃗∣r∣\hat{n} = \frac{\vec{r}}{|r|}n^=∣r∣r
n^=−5i+12j⃗(−5)2+(12)2\hat{n} = \frac{\vec{-5i+12j}}{\sqrt{(-5)^2+(12)^2}}n^=(−5)2+(12)2−5i+12j
= −5i+12j13\;\frac{-5i+12j}{13}13−5i+12j
