Circle Distance Question

This is my homework question:

Expand on your Circle class by adding a method called exactly dis开发者_如何学Pythont() which takes the x and y values of a point, and returns the distance of the point in coordinate space from the outside of the circle (or zero if the point is on or inside the circle).

The following code:

myCircle = Circle(1,1,1)
print myCircle.dist(3,4)

Should print an output of approximately:

2.6055512754639891

However I cant understand the question. What does it mean to return the point in coordinate space from the outside of the circle? Can you please explain it?

Find the distance between the center of the circle and the given point. Subtract the radius from the distance. Negative values are inside the circle.

You can easily check if the point is inside the circle on not. Once you've done that, and determined it is outside, you need to find a line normal to the circle and passing through the point. The length of the line from the circumference of the circle gives you the answer.

Hint: Any line passing through the center of the circle is normal to it.

So you have the point (x,y), radius r and center (x0,y0). I think you have enough information here to solve the problem :)

It probably means the distance to the closest point on the circle, so its a min-max problem wherre you are minimizing the distance of the point to circumfurance

>>> from math import hypot
>>> hypot(3-1,4-1)    # How far is the point from the centre of the circle?
3.6055512754639891
>>> hypot(3-1,4-1)-1  # Now subtract the radius
2.6055512754639891
>>>