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Polygon JKLM is drawn with vertices [tex]\( J (-4,-3), K (-4,-6), L (-1,-6), M (-1,-3) \)[/tex]. Determine the image coordinates of [tex]\( M' \)[/tex] if the pre-image is reflected across [tex]\( y=-5 \)[/tex].

A. [tex]\( M' (-1, -9) \)[/tex]
B. [tex]\( M' (-1, -7) \)[/tex]
C. [tex]\( M' (-1, -1) \)[/tex]
D. [tex]\( M' (1, -3) \)[/tex]


Sagot :

To solve this problem, we need to reflect the point [tex]\( M (-1, -3) \)[/tex] across the line [tex]\( y = -5 \)[/tex].

We start by analyzing the distance between the point [tex]\( M \)[/tex] and the reflection line [tex]\( y = -5 \)[/tex].

1. The y-coordinate of point [tex]\( M \)[/tex] is [tex]\( -3 \)[/tex], and the y-coordinate of the reflection line is [tex]\( -5 \)[/tex].
2. The distance between [tex]\( M \)[/tex] and the reflection line [tex]\( y = -5 \)[/tex] is calculated as follows:

[tex]\[ \text{Distance} = \text{y-coordinate of } M - \text{y-coordinate of the line} \][/tex]
[tex]\[ \text{Distance} = -3 - (-5) \][/tex]
[tex]\[ \text{Distance} = -3 + 5 \][/tex]
[tex]\[ \text{Distance} = 2 \][/tex]

3. To find the y-coordinate of the reflected point [tex]\( M^{\prime} \)[/tex], we need to place it the same distance away from the line [tex]\( y = -5 \)[/tex], but on the opposite side.
4. Subtract this distance from the line to find the y-coordinate of [tex]\( M^{\prime} \)[/tex]:

[tex]\[ \text{y-coordinate of } M^{\prime} = \text{y-coordinate of the line} - \text{Distance} \][/tex]
[tex]\[ \text{y-coordinate of } M^{\prime} = -5 - 2 \][/tex]
[tex]\[ \text{y-coordinate of } M^{\prime} = -7 \][/tex]

5. The x-coordinate remains unchanged during the reflection. Hence, the x-coordinate of [tex]\( M^{\prime} \)[/tex] is the same as that of [tex]\( M \)[/tex], which is [tex]\( -1 \)[/tex].

So, the coordinates of the reflected point [tex]\( M^{\prime} \)[/tex] are:

[tex]\[ M^{\prime} = (-1, -7) \][/tex]

From the given options, the correct one is:

- [tex]\( M^{\prime}(-1, -7) \)[/tex]

Thus, the image coordinates of [tex]\( M^{\prime} \)[/tex] are indeed [tex]\( (-1, -7) \)[/tex].