Originally Posted by

**FelixFelicis28** I'm heading off now so I'll leave you with this.

Tbh, I may have confused you by introducing vectors, sorry. :P The point is, we want a function of the position of the vehicles in terms of time, hence we parameterize the position of the vehicles.

If A is travelling east at 60mph then clearly after 1 hour, A has travelled 60 miles east, after 2 hours 120 miles east, 3 hours 180 miles east $\displaystyle \cdots$ after $\displaystyle t$ hours, $\displaystyle 60t$ miles east and $\displaystyle 0t$ miles north.

Similarly for B, after $\displaystyle t$ hours, it has travelled $\displaystyle 35t$ miles north and $\displaystyle 0t$ miles east.

Now pythagoras but **keep** your parameter (i.e. $\displaystyle t$) when you use pythagoras and you're done.