Matrix Transformations 58D414
1. **Problem 1: Transformation of figure ABCD under ERS**
Given points:
- A(-2, -2), B(-4, -1), C(-4, -3), D(-2, -3)
Transformations:
- $$E=\begin{bmatrix}-2 & 0 \\ 0 & -2\end{bmatrix}$$ (scaling by -2)
- $$R=\begin{bmatrix}0 & 1 \\ 1 & 0\end{bmatrix}$$ (reflection about line y=x)
- $$S=\begin{bmatrix}0 & -1 \\ -1 & 0\end{bmatrix}$$ (reflection and rotation)
We apply transformations successively in order ERS, meaning first S, then R, then E.
2. **Step 1: Apply S to each point**
For a point $$P=(x,y)$$, new point $$P' = S \times \begin{bmatrix}x \\ y\end{bmatrix} = \begin{bmatrix}0 & -1 \\ -1 & 0\end{bmatrix} \begin{bmatrix}x \\ y\end{bmatrix} = \begin{bmatrix}-y \\ -x\end{bmatrix}$$
Calculate:
- A: $$(-2,-2) \to (-(-2), -(-2)) = (2, 2)$$
- B: $$(-4,-1) \to (-(-1), -(-4)) = (1, 4)$$
- C: $$(-4,-3) \to (-(-3), -(-4)) = (3, 4)$$
- D: $$(-2,-3) \to (-(-3), -(-2)) = (3, 2)$$
3. **Step 2: Apply R to the results from Step 1**
For $$P'=(x', y')$$, new point $$P'' = R \times \begin{bmatrix}x' \\ y'\end{bmatrix} = \begin{bmatrix}0 & 1 \\ 1 & 0\end{bmatrix} \begin{bmatrix}x' \\ y'\end{bmatrix} = \begin{bmatrix}y' \\ x'\end{bmatrix}$$
Calculate:
- A: $$(2, 2) \to (2, 2)$$
- B: $$(1, 4) \to (4, 1)$$
- C: $$(3, 4) \to (4, 3)$$
- D: $$(3, 2) \to (2, 3)$$
4. **Step 3: Apply E to the results from Step 2**
For $$P''=(x'', y'')$$, new point $$P''' = E \times \begin{bmatrix}x'' \\ y''\end{bmatrix} = \begin{bmatrix}-2 & 0 \\ 0 & -2\end{bmatrix} \begin{bmatrix}x'' \\ y''\end{bmatrix} = \begin{bmatrix}-2x'' \\ -2y''\end{bmatrix}$$
Calculate:
- A: $$(2, 2) \to (-4, -4)$$
- B: $$(4, 1) \to (-8, -2)$$
- C: $$(4, 3) \to (-8, -6)$$
- D: $$(2, 3) \to (-4, -6)$$
**Final image coordinates of ABCD after ERS:**
- A'(-4, -4), B'(-8, -2), C'(-8, -6), D'(-4, -6)
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5. **Problem 2: Shear transformation on triangle ABC**
Given triangle ABC with vertices:
- A(2, 2), B(2, 0), C(3, 2)
Shear factor 3 parallel to the x-axis means the transformation matrix is:
$$\text{Shear} = \begin{bmatrix}1 & 3 \\ 0 & 1\end{bmatrix}$$
Apply shear to each point:
$$P' = \text{Shear} \times \begin{bmatrix}x \\ y\end{bmatrix} = \begin{bmatrix}x + 3y \\ y\end{bmatrix}$$
Calculate:
- A: $$(2, 2) \to (2 + 3 \times 2, 2) = (8, 2)$$
- B: $$(2, 0) \to (2 + 3 \times 0, 0) = (2, 0)$$
- C: $$(3, 2) \to (3 + 3 \times 2, 2) = (9, 2)$$
**Coordinates of A'B'C' after shear:**
- A'(8, 2), B'(2, 0), C'(9, 2)