Have you found the values of that corresponds to each pointa,bandp?

Once you find them you can consider differences of values of as distances between points on the line, that should help with finding the ratio.

Finding the values of forashould not be a problem

forp, your given it lies on so the position ofpis and you're given that OP it is perpendicular to the the line so , So now you can solve for

Bobak