Δdef  rotates 90° clockwise about point a to create δd  'e  'f. therefore, which equation must be true? m∠def = m∠d  'f  'e  '

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.

x=9

step-by-step explanation: