Let’s solve each reflection problem step by step. We’ll find the new coordinates of each shape after reflecting it over the given line.
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Problem 1: Reflection Across Line y = -x
Original points (from graph):
Looking at the green L-shape in quadrant III:
- Bottom-left corner: (-3, -4)
- Top-left corner: (-3, -2)
- Bottom-right corner: (-1, -4)
Rule for reflection over
y = -x:
Swap x and y, then change both signs → (x, y) → (-y, -x)
Apply to each point:
- (-3, -4) → (4, 3)
- (-3, -2) → (2, 3)
- (-1, -4) → (4, 1)
So reflected points are: (4,3), (2,3), (4,1)
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Problem 2: Reflection Across Line y = x
Original triangle points (in quadrant II):
From graph:
- (-4, 2)
- (-2, 3)
- (0, 1)
Rule for reflection over
y = x: Swap x and y → (x, y) → (y, x)
Apply:
- (-4, 2) → (2, -4)
- (-2, 3) → (3, -2)
- (0, 1) → (1, 0)
Reflected points: (2,-4), (3,-2), (1,0)
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Problem 3: Reflection Across the line x = 1
Original shape (green polygon in quadrant I):
Points from graph:
- (1, 2)
- (1, 4)
- (4, 4)
- (4, 3)
- (2, 3)
- (2, 2)
To reflect over vertical line
x = 1, use formula:
New x = 1 - (original x - 1) = 2 - original x
Keep y same.
So: (x, y) → (2 - x, y)
Apply:
- (1,2) → (2-1, 2) = (1,2) ← stays on line
- (1,4) → (1,4) ← stays
- (4,4) → (2-4,4) = (-2,4)
- (4,3) → (-2,3)
- (2,3) → (0,3)
- (2,2) → (0,2)
Reflected points: (1,2), (1,4), (-2,4), (-2,3), (0,3), (0,2)
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Problem 4: Reflection Across the y-axis
Original triangle (quadrant I):
Points:
- (1,1)
- (1,4)
- (5,1)
Rule for reflection over
y-axis: Change sign of x → (x,y) → (-x, y)
Apply:
- (1,1) → (-1,1)
- (1,4) → (-1,4)
- (5,1) → (-5,1)
Reflected points: (-1,1), (-1,4), (-5,1)
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Problem 5: Reflection Across the line y = 2
Original parallelogram (quadrant I):
Points:
- (1,3)
- (2,5)
- (5,5)
- (4,3)
To reflect over horizontal line
y = 2:
New y = 2 - (original y - 2) = 4 - original y
Keep x same.
So: (x, y) → (x, 4 - y)
Apply:
- (1,3) → (1, 4-3) = (1,1)
- (2,5) → (2, 4-5) = (2,-1)
- (5,5) → (5,-1)
- (4,3) → (4,1)
Reflected points: (1,1), (2,-1), (5,-1), (4,1)
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Problem 6: Reflection Across the x-axis
Original L-shape (quadrant IV):
Points:
- (2,-5)
- (2,-3)
- (4,-3)
- (4,-2)
- (5,-2)
- (5,-4)
Rule for reflection over
x-axis: Change sign of y → (x,y) → (x, -y)
Apply:
- (2,-5) → (2,5)
- (2,-3) → (2,3)
- (4,-3) → (4,3)
- (4,-2) → (4,2)
- (5,-2) → (5,2)
- (5,-4) → (5,4)
Reflected points: (2,5), (2,3), (4,3), (4,2), (5,2), (5,4)
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Final Answer:
1) Reflected points across y = -x: (4,3), (2,3), (4,1)
2) Reflected points across y = x: (2,-4), (3,-2), (1,0)
3) Reflected points across x = 1: (1,2), (1,4), (-2,4), (-2,3), (0,3), (0,2)
4) Reflected points across y-axis: (-1,1), (-1,4), (-5,1)
5) Reflected points across y = 2: (1,1), (2,-1), (5,-1), (4,1)
6) Reflected points across x-axis: (2,5), (2,3), (4,3), (4,2), (5,2), (5,4)
Parent Tip: Review the logic above to help your child master the concept of translation and reflection worksheet answers.