I'm still unable to come up with a formula in terms of x1 and x2 However in the next problem I'm given values for the variables.
x1 = 30 x2 = 40
and the distance between x1 and x2 = 100.
So using what we know about right triangles, I found these values:
sorry, the drawing isn't to scale.
Using the arcsine function, I found that angle P is 21.801
and angle q is 16.999
So, in solving for y
y CSC (16.99) + y CSC (21.801) = 100
Using algebra I get
y = 100/( CSC (16.99) + CSC (21.801))
Which comes out to about 16.2002 for the length of y
Does that seem right?
I apologize for how messy and incoherent that probably was.