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Geometry

Reflection

A reflection flips a figure over a line of reflection. Over the x-axis: (x, y) → (x, −y). Over the y-axis: (x, y) → (−x, y). Over y = x: (x, y) → (y, x).

Reflection is like looking in a mirror — the image is flipped but the same distance from the line!

Visualize It

Reflection flips a figure over a line

xyABCA'B'C'O
OriginalReflectedMirror line

Watch & Learn

Watch a clear, friendly video explanation of Reflection:

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Worked Examples

Follow along with these step-by-step examples. Take your time — there's no rush!

1Example 1

Problem

Reflect (4, −3) over the x-axis

Reflect over x-axis

xyABCA'B'C'O
OriginalReflectedMirror line

Step-by-Step Solution

1

Over x-axis: (x, y) → (x, −y)

2

(4, −3) → (4, 3)

Answer

(4, 3)

2Example 2

Problem

Reflect (−2, 5) over the y-axis

Reflect over y-axis

xyABCA'B'C'O
OriginalReflectedMirror line

Step-by-Step Solution

1

Over y-axis: (x, y) → (−x, y)

2

(−2, 5) → (2, 5)

Answer

(2, 5)

3Example 3

Problem

Reflect (3, 7) over the line y = x

Reflect over y = x

xyy=xABCA'B'C'O
OriginalReflectedMirror line

Step-by-Step Solution

1

Over y = x: (x, y) → (y, x)

2

(3, 7) → (7, 3)

Answer

(7, 3)

4Example 4

Problem

Reflect the point (−5, −2) over the x-axis

Reflect (−5,−2) over x-axis

xyABCA'B'C'O
OriginalReflectedMirror line

Step-by-Step Solution

1

Over x-axis: (x, y) → (x, −y)

2

(−5, −2) → (−5, 2)

Answer

(−5, 2)

5Example 5

Problem

A triangle has vertices (1, 2), (3, 4), (5, 1). Reflect over the y-axis.

Triangle reflected over y-axis

xyABCA'B'C'O
OriginalReflectedMirror line

Step-by-Step Solution

1

Over y-axis: (x, y) → (−x, y)

2

(1, 2) → (−1, 2)

3

(3, 4) → (−3, 4)

4

(5, 1) → (−5, 1)

Answer

(−1, 2), (−3, 4), (−5, 1)

Your Turn — Practice Problems

Try all 5 problems on your own first. Write out your work — that's how it sticks!

💡 Tip: Don't peek at the answers until you've genuinely tried each one.

1

Reflect (5, 2) over the x-axis

2

Reflect (−4, 6) over the y-axis

3

Reflect (1, 8) over y = x

4

Reflect (−3, −5) over the x-axis

5

Reflect (7, 0) over the y-axis

6

Reflect (0, 4) over the x-axis

7

Reflect (−2, 3) over y = x

8

Reflect (6, −1) over the y-axis

9

Reflect (−5, 0) over the x-axis

10

Reflect (4, 9) over y = x

11

Reflect (−3, −7) over the y-axis

12

Reflect (2, 2) over y = x

Finished all 12? Give yourself a pat on the back — then check your work!

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