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 )
Those crafty little weasels. If two lines are perpendicular to the same line, we know that they're parallel. If we take another look at the perpendicular lines, we'll see that we have four sets of parallel lines here as well: a || d, b || g, c || f, and e || h. Seeing these relationships among segments and angles makes it possible to find angle measures and side lengths in polygons.