oh I see, yes I think I agree, but that's what we're after isn't it? the circle to be circular in terms of surface distance around the center point, which as you say means it will be non-circular in terms of degrees of lat/lng? whereas if you made it a circle based on degrees then when you came to cycle it then E-W would be a lot shorter than N-S at our latitudes.
Precisely. Drawing a circle on a map and getting the coordinates that way obviously works fine. However actually calculating them means having to convert between km and degrees, which is definitely not straightforward.
My maths isn't great, but I can visualise geometric problems pretty well.
oh I see, yes I think I agree, but that's what we're after isn't it? the circle to be circular in terms of surface distance around the center point, which as you say means it will be non-circular in terms of degrees of lat/lng? whereas if you made it a circle based on degrees then when you came to cycle it then E-W would be a lot shorter than N-S at our latitudes.