Can the outer corner at the base of an isosceles triangle be obtuse? Why?

An isosceles triangle is a triangle in which the angles at the base are equal, while these angles are less than 90 degrees (since the sum of the angles of the triangle is 180 degrees), which means the angles at the base are acute;
The outer corner of a triangle is the angle that is adjacent to the inner corner of the triangle at the same vertex;
So, if we consider one of the angles at the base, then we can conclude that an adjacent angle with an acute angle will always be obtuse, therefore the outer angle at the base of an isosceles triangle is obtuse.