Determine the scale factor going from Triangle 1 (ABC) to Triangle 2 (A'B'C'). Take measurements as needed.
Determine the scale factor going from Triangle 2 (A'B'C') to Triangle 3 (A''B''C''). Take measurements as needed.
Determine the scale factor going from Triangle 1 (ABC) to Triangle 3 (A''B''C''). Take measurements as needed.
Do you see a relationship between the value of the scale factor going from Triangle 1 to Triangle 3 and the scale factors determined going from Triangle 1 to Triangle 2, and Triangle 2 to Triangle 3?