Reflections in the Coordinate Plane

This video tutorial by Kirk Weiler covers reflections in the coordinate plane, focusing on exercises involving triangles and trapezoids. It explains how to reflect shapes across the x-axis, y-axis, and other lines, emphasizing the properties of reflections, such as perpendicular bisectors. The tutorial includes practical exercises to reinforce understanding of reflection rules and concepts.

What is the primary difference between reflections in the Euclidean plane and the coordinate plane?

• Use of algebraic rules in the coordinate plane

• Use of tracing paper in the coordinate plane

• Use of a mirror in the Euclidean plane

• No difference, they are the same

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What happens to the x-coordinate when reflecting a point across the y-axis?

• Its sign is reversed

• It is doubled

• It remains unchanged

• It becomes zero

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CCSS.8.G.A.3

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After reflecting a triangle across the y-axis, how are the line segments connecting original points to their images related to the y-axis?

• Perpendicular

• Identical

• No specific relation

• Parallel

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CCSS.8.G.A.3

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What is the rule for reflecting a point across the x-axis?

• No change is needed

• Swap the x and y coordinates

• Change the sign of the y-coordinate

• Change the sign of the x-coordinate

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When reflecting a point across the y-axis, what happens to the y-coordinate?

• It is doubled

• It is halved

• It remains the same

• It is negated

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CCSS.8.G.A.3

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In a reflection across a horizontal line other than the x-axis, what must you do to find the image of a point?

• Change the y-coordinate to zero

• Count the distance from the line and reflect accordingly

• Swap the x and y coordinates

• Reflect across the x-axis instead

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What type of line is y = 3 considered?

• Non-linear

• Diagonal

• Horizontal

• Vertical

How do you determine the line of reflection when reflecting a shape?

• By finding the midpoint of connected preimage and image points

• By using the highest point of the shape

• By guessing the approximate center

• By measuring the area around the shape

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CCSS.8.G.A.3

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What is the equation of a vertical line passing through points (-2, 2), (-2, 9), and (-2, 7)?

• y = 2

• x = -2

• x = 2

• y = -2

Why is reflecting across the x or y axis considered simpler than other lines?

• Because no counting or plotting is needed

• Because it requires advanced mathematics

• Because it changes both coordinates

• Because it doesn't involve real reflection

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CCSS.8.G.A.3

CCSS.HSG.CO.A.5