Question about length of hyperbolic line segment in sect 2.4

In section 2.4 an expression is given to find the hyperbolic distance between two points A and B on a Poincare disc representation of hyperbolic space.

Where P and Q are points on the boundary circle of the disc where the hyperbolic line through points A and B terminate, and QA, QB, PA, and PB are the Euclidean distances between points Q and A, Q and B etc.

Is the Euclidean distance mentioned here the Euclidean straight line distance between the various points, or the Euclidean arc length along the circle representing the hyperbolic line?