With isosceles triangles you can split them in two so they are symmetrical.
This means that you are left knowing 12/2 = 6 degrees at the smallest angle and one side remains as 0.5
Now that we have a right angled triangle can use SohCahToa to find our formula: sin(6) = x/0.5
Now we can re-arrange the equation to x = 0.5*sin(6) to get a grand total of ~0.1

Thanks WeeklyShoe for correcting me on the rearrangement (it is correct now)