its pythagorean theorem

let's use the pythagorean theroem
x²+x²=10²
=
2x²=100
x²=50
x=sqrrt(50)
x = sqrrt(2) × sqrrt(25)
x= 5 × sqrrt(2)
so it's to draw a halfmoon
remark, x is length, it shouldn't be negative valued, therefore, there is only 1 solution and it is:
x= 5 × sqrrt(2)