References: 1  Royal College of Radiologists. 2  Swinson S, Tapp M, Brindley R, Chapman S, Offiah A, Johnson K. An audit of skeletal surveys for suspected non-accidental injury following publication of the British Society of Paediatric Radiology guidelines. 3  Offiah AC, Hall CM.
The question of distance between two straight lines arises only when they are parallel. The given lines are parallel. If the equations of parallel lines are ax + by + c = 0 and ax + by + c' = 0, then the perpendicular distance between them is given by. p = l c - c' l / sqrt ( a^2 + b^2 )
Ignoring curvature of the earth, and assuming a mean Earth radius of 3960 miles, then the distance between lines of longitude that are 1 degree apart = 3960 * 2 * pi /360 * cosine (of latitude) in miles. At the equator it is about 69 miles, at the poles it is zero. Ignoring curvature of the earth, and assuming a mean Earth radius of 3960 miles, then the distance between lines of longitude that are 1 degree apart = 3960 * 2 * pi /360 * cosine (of latitude) in miles.