Answer:
Similar: First two shapes only
Step-by-step explanation:
Triangle Similarity Theorems
There are three triangle similarity theorems that specify under which conditions triangles are similar:
If two of the angles are congruent, the third angle is also congruent and the triangles are similar (AA theorem).
If the three sides are in the same proportion, the triangles are similar (SSS theorem).
If two sides are in the same proportion and the included angle is equal, the triangles are similar (SAS theorem).
The first pair of shapes are triangles that are both equilateral and therefore have all of its interior angles of 60°. The AAA theorem is valid and the triangles are similar.
The second pair of shapes are parallelograms. The lengths are in the proportion 6/4=1,5 and the widths are in proportion 3/2=1.5, thus the shapes are also similar.
The third pair of shapes are triangles whose interior acute angles are not congruent. These triangles are not similar
