3. A rotation was performed on AGHI to transform it to AG'H'I', shown below.
G
-11 -10 -9
-8
r
101
9
8
7
6
"5
4
3
+
-6
-5
4
-3
-2
-1
0
2
3
4
5
6
8
9
+
-2
3
H
4
6
-7
GS
9
10
14
-12
What rotation angle was used and how can you prove that the two triangles are
congruent?