Let the height of BC side of △ABC be AD=h, then

h=AB/2= 1

AC>h，

So c has two positions ∠BAC also has two degrees.

It is easy to know that ∠ ACD = 45.

When ∠ BAC < ∠ bad, ∠ BAC = ∠ ACD-∠ ABC = 15.

When ∠ BAC > ∠ bad, ∠ BAC =180-(∠ ABC+∠ ACD) =105.

thank you