Question

ΔDEF rotates 90° clockwise about point A to create ΔD 'E 'F. Therefore, which equation must be true?
m∠DEF = m∠D 'F 'E '
m∠D 'E 'A ' = m∠DAE
m∠EAE ' = m∠FAF '
m∠DAE m∠E 'AF '

Answer 1

any idea ?

try drawing it - will be more easy understandably

Answer 2

old question but will answer so this can be closed

for rotations, corresponding angle measures are conserved

ex: if we translate angle <ABC, then <A'B'C' will have the same measure (but not necessarily other angles like <B'A'C' etc. try to apply this logic to your problem.