Answer:
similarity
Step-by-step explanation:
look , dude
the two triangles have the following features:
the angle B= angle C = 90 degree
the angle A= the angle F
so the third angle in the first triangle = the third angle in the second triangle
so you have one condition of similarity which is the three angles are equal
to get the answer for lengths :
ab/fe= constant of proportionality
thus ab/fe=2.5/5=.5
so ac/13=.5 thus ac=6.5
and 6/de=.5 so de=12
