Transformations on the Coordinate Plane
A free Geometry lesson from the “Coordinate Geometry and Proof” unit, with a worked example and practice problems including step-by-step solutions.
Transformations move figures while preserving or changing their position. Translations slide, reflections flip, and rotations turn around a point.
What you'll learn
- Translate points
- Reflect points
- Rotate points around the origin
Worked example
Problem. Reflect (4, -7) across the x-axis.
- A reflection across the x-axis keeps x the same.
- The y-coordinate changes sign.
- (4, -7) becomes (4, 7).
Answer: (4, 7)
Practice problems
1. Translate (2, 5) right 3 and down 4.
Choices: (5, 1) · (-1, 9) · (5, 9) · (-1, 1)
Show solution
- Warm-up: First identify exactly what the question is asking: Translate (2, 5) right 3 and down 4.
- Compare each answer choice with the calculation or rule, and eliminate choices that do not satisfy the condition.
- Add 3 to x and subtract 4 from y.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: (5, 1)
2. Reflect (-3, 8) across the x-axis.
Choices: (-3, -8) · (3, 8) · (3, -8) · (-8, -3)
Show solution
- Warm-up: First identify exactly what the question is asking: Reflect (-3, 8) across the x-axis.
- For signed numbers, track both distance from zero and direction so the sign of the answer makes sense.
- Keep x, change y's sign.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: (-3, -8)
3. Reflect (-6, -2) across the y-axis.
Choices: (6, -2) · (-6, 2) · (6, 2) · (-2, -6)
Show solution
- Core Practice: First identify exactly what the question is asking: Reflect (-6, -2) across the y-axis.
- For signed numbers, track both distance from zero and direction so the sign of the answer makes sense.
- Change x's sign, keep y.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: (6, -2)
4. Rotate (4, 1) 180 degrees about the origin.
Choices: (-4, -1) · (-1, 4) · (1, -4) · (4, -1)
Show solution
- Core Practice: First identify exactly what the question is asking: Rotate (4, 1) 180 degrees about the origin.
- Compare each answer choice with the calculation or rule, and eliminate choices that do not satisfy the condition.
- A 180-degree rotation changes both signs.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: (-4, -1)
5. Which transformation preserves size and shape?
Choices: Reflection · Dilation by 2 · Stretch only x · Changing one side
Show solution
- Challenge: First identify exactly what the question is asking: Which transformation preserves size and shape?
- Compare each answer choice with the calculation or rule, and eliminate choices that do not satisfy the condition.
- Reflections are rigid motions.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: Reflection
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