dodecahedron.js

var s1 = Math.sin(Math.PI*0.4),
    s2 = Math.sin(Math.PI*0.8),
    c1 = Math.cos(Math.PI*0.4),
    c2 = Math.cos(Math.PI*0.2),
    L = 1500,
    one = 1500 / (s1*2),
    a = one*s2*2;

console.log([
[one*s1, one*(1+c2)],
[one*s1*2, one*(c1+c2)],
[one*(s1+s2), 0],
[one*(s1-s2), 0],
[0, one*(c1+c2)]
]);

console.log(0.1*a*Math.sqrt(25-10*Math.sqrt(5)));