Algodoo

Please explain how you derived that number. That might help to determine if, in fact, it's irrational.

The number is equal to the Y coordinate of point C. The line is length 1, not 0.8662

The line should be a line from C to the X axis, which is length 0.8662, we can calculate the algebraic form of Y using X = 0.5 in point C, Y = sqrt(3) / 2 = 0.8662 which is irrational

*0.8662 is just the short version of the irrational number in the scene

Your explanation sounds rational! Thanks 42flowermaster