I have been working on a kitchen remodel in RL. The lighting over the sink peninsula was was a real problem in design. I want the pendants to hang parallel. If you look at the picture from the manufacturer, (LBL Lighting), 2 of the pendants are not on the rail system, but direct wired to a ceiling fixture.
Although you cannot see, I built the counters according to the measurements in RL. The sink is off center. I played with curves until I found what worked with the length and width of the counter, and on a grid, it was easy to see where the alignment of the 3 pendants worked out. I was ready for new lighting in my SL home, so I built it! Below are the results. I ended up using a rusty corroded metal texture to simulate the "Jelly" pendant. I know there is a mathematical way of figuring this out, but I hardly remember to try to use circles radii, let alone arcs. The rail pieces ended up being sections of a circles stretched and cut until I got it!