Hello,

I need help with the following question. I couldn't find a equation for the distance between the trains. How do i deal with train A is 70km north of train B? and trains traveling in different direction.

At 8 am, train A is 70km north of train B. Train A traveling west at 50km/h and train B traveling east at 60km/h. How fast is the distance between the trains changing at 12 pm.

I have my diagram here

known rates

da/dt = 50km/h

db/dt = 60km/h

unknown rates

dc/dt t=4

Help and Thanks

I solved myself, I just noticed i can form a triangle with a+b .