1. **State the problem:**
We have points A(10,10) and B(-2,14).
Point A is reflected about the x-axis to get A'.
Point B is rotated anticlockwise about the origin by 90° to get B'.
We need to find the coordinates of A' and B' and prove that line segment AB is parallel to A'B'.
2. **Find coordinates of A' (reflection about x-axis):**
Reflection about the x-axis changes the y-coordinate sign but keeps x the same.
So, if A = (x, y), then A' = (x, -y).
Given A = (10, 10),
$$A' = (10, -10)$$
3. **Find coordinates of B' (90° anticlockwise rotation about origin):**
The formula for 90° anticlockwise rotation of a point $(x, y)$ about the origin is:
$$B' = (-y, x)$$
Given B = (-2, 14),
$$B' = (-14, -2)$$
4. **Prove AB is parallel to A'B':**
Two lines are parallel if their direction vectors are scalar multiples.
Calculate vector $\overrightarrow{AB}$:
$$\overrightarrow{AB} = (x_B - x_A, y_B - y_A) = (-2 - 10, 14 - 10) = (-12, 4)$$
Calculate vector $\overrightarrow{A'B'}$:
$$\overrightarrow{A'B'} = (x_{B'} - x_{A'}, y_{B'} - y_{A'}) = (-14 - 10, -2 - (-10)) = (-24, 8)$$
Check if $\overrightarrow{A'B'}$ is a scalar multiple of $\overrightarrow{AB}$:
$$\frac{-24}{-12} = 2, \quad \frac{8}{4} = 2$$
Both ratios are equal, so:
$$\overrightarrow{A'B'} = 2 \times \overrightarrow{AB}$$
Therefore, $AB$ is parallel to $A'B'$.
**Final answers:**
- Coordinates of $A'$: $(10, -10)$
- Coordinates of $B'$: $(-14, -2)$
- $AB$ is parallel to $A'B'$ because their direction vectors are scalar multiples.
Reflection Rotation Dd7575
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