21-28 please geometry

9514 1404 393

  21–24 and 28 are correctly marked

  25: NEI; 26: ASA or LA; 27: SSS

Step-by-step explanation:

25: At least one side is required for showing congruence. In figure 25, only angles are shown congruent, so there is not enough information.

__

26: Two angles and the side between them are marked congruent. These triangles can be declared congruent by ASA. Considering they are right triangles, one could also invoke LA as the appropriate theorem.

__

27: The unmarked sides of the two outside triangles can be shown to be congruent by virtue of the fact they are opposite congruent angles in the middle triangle. Hence all three sides can be shown congruent for those outside triangles, and the SSS postulate can be invoked.