In a circle, straight lines are said to be equally far from the center when the perpendiculars drawn to them from the center are equal.
Chords are said to be equally distant from the center (or equally far from the center), if the perpendiculars constructed to them from the center are equal in length, i.e. congruent.
In the following figure, the chords \(\overline{AB}\) and \(\overline{CD}\) are equally distant from the center, because the segments perpendicular to the chords have the same length \(a\) (i.e. they are congruent):