Coaxial Cable Bundling

Problem #56

Tags: geometry

Who solved this?

Previous:Caber Tossing in the Garden Next:Off-Axis Cable Bundling


Jakob works as a Quality Assurance technician at a factory which creates custom-made coaxially-bundled cables for specialty uses. To construct a cable bundle, an assembly worker performes the following steps:

Here are some cross-sections of completed cable bundles:

Cable Bundle n7

Cable Bundle n7

A cross-section of a completed coaxial cable bundle:
a copper core in Yellow (with diameter D),
7 rods in Red (each with diameter d),
a tube sleeve in Blue (with total diameter T).

Notice how every rod touches the core, the tube wall, and both adjacent rods. The values of D, N, and d must be chosen carefully to ensure that this happens, or else the bundle will not work properly. Here are some more examples of valid bundles:

Cable Bundle n7 Cable Bundle n7 Cable Bundle n7

More valid cable bundles.

And here is an example of an invalid bundle:

Cable Bundle n7

An invalid cable bundle. Notice the gap between two of the red rods.

Also note the yellow core and the blue tube both share the same centerpoint, shown in the above pictures in Black. As these are three-dimensional objects, the black dot represents the centerline axis shared by the core and the tube, and that is why they are called coaxial cable bundles.

Problem Statement

Recently the factory where Jakob works has purchased an automatic packaging and labeling machine. An assembly worker places a completed cable bundle into the machine and types in the parameters T D N d. The machine then affixes plugs to each end of the cable, coils the cable, places the cable into a box, and then labels the box with the information T D N d so that the buyer can know the type of cable is inside.

At the end of the day Jakob inspects each box before shipping them out to be sold, but one day Jakob notices that the label machine must have become misaligned, as several boxes are only labeled with the values T D and are completely missing the values N d. Relabeling each box wouldn't take a large amount of time, but Jakob then realizes that he would be unable to open the cable to count and measure the rods without destroying the cable tubing and thus rendering the expensive cable defective.

Given T and D, calculate both N and d so that the boxes can be re-labeled without destroying the cables.

Input Data
First line will be Q, the quantity of testcases.
Q lines will then follow, each with two space-separated values in the format T D.

Answer
Should consist of Q pairs of values in the format N d corresponding corresponding to the quantity and diameters of the rods around the copper core in each testcase.
N will always be an exact integer.
Error in d should be less than 1e-3.

Example

inpug data:
2
3 1
5.511 3.8

answer:
6 1 17 0.855
You need to login to get test data and submit solution.