Hi there!
In order to prove these two triangles similar, we could use the SAS similarity theorem. This is because on the smaller triangle, we have 15 and 20, as well as an included 90 degree angle. On the bigger triangle, we have proportional sides to the 15 and 20 sides, as well as an included 90 degree angle.
ANSWER:
SAS Similarity Theorem
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!
