In an isosceles triangle with two equal angles, if one of the angles is 30°, what is the vertex angle?

Which condition is NOT sufficient to prove that two triangles are congruent?

Which of the following pairs of triangles can be proven congruent using the SAS criterion?

If two triangles have two corresponding sides of the same length and the included angle is different, what can be said about the triangles?

What method can be used to verify whether two triangles are congruent if they can be physically cut out?