a*b = a+b/2
a-b = 1
(1+b)*b = (1+b)+b/2
b+b² = 1+2b/2
2b+2b²/2 = 1+2b/2
2b+2b² = 1+2b
2b² = 1
b² = 1/2
b = 0,7071067811865475
a = 1+b
a = 1, 7071067811865475