Rotation Math Example 4

Solution

1. 1
   Step 1: Translate so the center of rotation $(1,0)$ becomes the origin: subtract $(1,0)$ from all vertices.
2. 2
   Step 2: $A \to (0,0)$, $B \to (2,0)$, $C \to (1,2)$.
3. 3
   Step 3: Apply 90° CCW rule $(x,y)\to(-y,x)$: $A\to(0,0)$, $B\to(0,2)$, $C\to(-2,1)$.
4. 4
   Step 4: Translate back by adding $(1,0)$: $A'=(1,0)$, $B'=(1,2)$, $C'=(-1,1)$.