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

• MrEquation: The equation that is given does not have to be true, because the letters are not in the same order. Therefore, we are not comparing the corresponding pairs of angles. They may or may not be congruent.
  
  When a shape is rotated, the corresponding pairs of angles are congruent.
• :

  As Rotation does not bring any changes in the shape and size of a geometrical figure.

  So, the two triangles , ΔDEF→→Called Pre image

  when rotated through an angle of 90°, will be congruent to

  , ΔD'E'F'→→→Called Image.

  →So, when two triangles are congruent , their corresponding parts will be equal ,that is congruent.

  1. ∠FD E≅∠F' D'E'

  2.∠DEF≅∠D'E'F'

  3.∠E FD≅∠E'F'D'

  4. ED≅E'D'

  5. F E=F'E'

  6.  FD=F'D'

  All six possibilities are true when, ΔDEF rotates 90° clockwise about point A to create ΔD 'E 'F.