4) Which pair of triangles is congruent by Angle - Angle- Side?

Answer:
SAS (Side-Angle-Side): If two pairs of sides of two triangles are equal in length, and the included angles are equal in measurement, then the triangles are congruent.
We want to see which pair of triangles is equivalent by the Angle-Angle-Side criteria.
The correct option is 2, where we have two equal angles, and the bottom side is equal in both triangles.
The Angle-Angle-Side criteria means that if two triangles have an equal side, and the two correspondent angles also are equal, then these triangles are equivalent.
So we just need to see (by notation, not by how the triangles look like) in which ones we have two equal angles and one equal side.
That one is the second pair of triangles.
We can see that the two top angles are equal (two curves) and that the left angle in the left triangle is equal to the right angle on the other triangle (so we have two equal angles).
Also, the bottom side is equal on both triangles.
Then the angle-angle-side criteria is meet, meaning that these two triangles are equivalent.
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