calculate 2 points on an outer circle based on 2 points on an inner circle where the 2 sets of points are horizontal

Question

Observing the diagram through the link below, where the 2 circles have the same center point:

http://www.graphicsgen.com/CircleQuestion.png

given the center point (X1,Y1), any radius S, and degrees D and E, it is easy to calculate Points (X2,Y2) and (X3,Y3), as follows:

var X2 = X1 + S * (Math.cos(D * (Math.PI / 180)));
var Y2 = Y1 + S * (Math.sin(D * (Math.PI / 180)));
var X3 = X1 + S * (Math.cos(E * (Math.PI / 180)));
var Y3 = Y1 + S * (Math.sin(E * (Math.PI / 180)));

So given that lines (X2,Y2),(X4,Y4) and (X3,Y3),(X5,Y5) are horizontal and both perpendicular to (X2,Y2),(X3,Y3), how do you calculate points (X4,Y4) and (X5,Y5) given any radius R?

Thanks