Answer:
100 miles
Step-by-step explanation:
Relative Speed: 60+40=100 mph
you can think that one train is stationary,another one is 100 mph
so one hour before the train pass each other，the distance is 100 miles
Answer:
On the right is a circle with centre (0, 0), radius r and (x, y) any point on the circle. Distance between (0,0) and (x, y) equals the radius, r. If the centre is (0, 0), the equation of the circle will be of the form x2 + y2 = r2.
