Reflections Quick Check 4 of 54 of 5 Items Question Use the image to answer the question. What are the coordinates of Y′ after a reflection across y=1 ? (1 point) Responses Y′(−2,−1) upper Y prime left parenthesis negative 2 comma negative 1 right parenthesis Y′(−2,3) upper Y prime left parenthesis negative 2 comma 3 right parenthesis Y′(4,−1) upper Y prime left parenthesis 4 comma negative 1 right parenthesis Y′(4,5) upper Y prime left parenthesis 4 comma 5 right parenthesis Skip to navigation page 19 of 19

1 answer

To determine the coordinates of point \( Y' \) after a reflection across the line \( y = 1 \), we first need to understand how a reflection works with respect to a horizontal line.

For a point with coordinates \( (x, y) \), when reflecting across the line \( y = k \) (in this case \( k = 1 \)), the new y-coordinate \( y' \) can be found using the formula: \[ y' = k - (y - k) = 2k - y \] where \( k \) is the y-coordinate of the line we are reflecting across.

  1. Identify the original point \( Y(x, y) \) (though it isn't specified in your question, we'll denote it generally).
  2. Calculate the new y-coordinate after reflection using \( y' = 2(1) - y = 2 - y \).
  3. The x-coordinate remains unchanged.

Assuming we are reflecting an unknown point \( Y(x, y) \), we can compare our results against the provided responses.

Let's evaluate the responses:

  1. \( Y'(-2, -1) \) → y-coordinate: -1 → needs calculation: \( 2 - (-1) = 3 \) (not correct)
  2. \( Y'(-2, 3) \) → y-coordinate: 3 → needs calculation: \( 2 - 3 = -1 \) (not correct)
  3. \( Y'(4, -1) \) → y-coordinate: -1 → needs calculation: \( 2 - (-1) = 3 \) (not correct)
  4. \( Y'(4, 5) \) → y-coordinate: 5 → needs calculation: \( 2 - 5 = -3 \) (not correct)

To find the correct answer, I would need the original coordinates of point \( Y \) to check which response corresponds.

Could you please provide the coordinates of point \( Y \)? This will allow us to accurately find \( Y' \).