
Arash S. answered 11/20/19
Professional Structural Engineer and Experienced Academic Tutor
Put t=0 in Robin's moving equation. That gives you (-3,5) which is the point from which Robin starts to move. Now consider that for every hour Robin is moving 6 Km up and 8 Km to the right. Using Pythagoras theorem, he moves 10 Km every hour. After two hours, he's 20 Km away from the origin. AT this point Casey reaches the same origin from which Robin started. So, Casey is always 2 hour behind Robin. Thus, Casey's moving equation will be:
rule(x,y) = (-3+8*(t-2),5+6*(t-2))
which is:
rule(x,y) = (-19+8*t,-7+6*t)