Hi Jayanti,
I am not sure what your first question is. We use the distance formula to find the distance between any 2 points (x1, y1) and (x2, y2):
D^2= (x1 - x2)^2 + (y1 - y2)^2 OR
D= sqrt[(x1 - x2)^2 + (y1 - y2)^2]
In this case the distance is from the center to the outside of the circle, so it happens to be the radius.
For distance vs. slope it is difficult to generalize but I would just look for either those words exactly, or related keywords (these are just some examples, not guarantees):
Distance: Length, Far, Side
Slope: Change, Increase, Decrease
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