I found that applying sine rule has a disadvantage, especially when you want to find one of the angles and the angle is an obtuse angle.
For example, consider a triangle ABC
Angle B = 30 degrees
AB = AC = 1 cm
The problem arises here,
I tried to use sine rule to get Angle A,
But in fact, angle A should be 120 degrees, because the calculator will give an acute angle instead of obtuse angle.
Is there any way to avoid this kind of mistake