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Symmetry Song for Kids | A Day at Symmetry Land | Lines of Symmetry

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Folding Test: investigating lines of reflection symmetry

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Investigating if the chosen shape has lines of symmetry and, if it has, determining the number of these lines simulating folding shape along various ...

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Randomised reflection questions with automatic checking

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Reflect the polygon over each axis to create an image in each of the four quadrants.

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Messing With Lisa: Introduction to Transformations

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manual digital

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Matematică pentru clasa a V-a - Unitatea 8

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Reflection is a transformation in which a figure is reflected across a line, creating a mirror image. For example:

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- [Instructor] We're asked to plot the image of point A under a reflection across the line l. So we have our line l here, and so we wanna plot the image of here, we wanna plot the image of point A under a reflection across line l. Well, one way to think about it is point A is exactly one, two, three, four units to the right of l. And so its reflection is going to be four units to the left of l. So if we go one, two, three, four, that would be the image of point A. We could maybe denote that as A prime. So if you're doing this on the Khan Academy exercise, you would actually just click on a point right over there, and it would show up. But this would be the reflection of point A across the line l. Let's do another example. So here we're asked plot the image of point B under a reflection across the x-axis. Alright, so this is point B, and we're going to reflect it across the x-axis right over here. So to go from B to the x-axis, it's exactly five units below the x-axis. One, two, three, four, five. So if we were to reflect across the x-axis, essentially create its mirror image, it's going to be five units above the x-axis. One, two, three, four, five. So that's where the image would be. Maybe we could denote that with a B prime. We are reflecting across the x-axis. Let's do another example. So here they tell us point C prime is the image of C, which is at the coordinates negative four comma negative two, under a reflection across the y-axis. What are the coordinates of C prime? So pause this video and see if you can figure it out on your own. So there's several ways to approach it. It doesn't hurt to do a quick visual diagram. So that could be my x-axis. This would be my y-axis. And it's the point negative four comma negative two, so that might look like this. Negative four, negative two. So this is the point C right over here. And we wanna reflect across the y-axis. So we wanna reflect across the y-axis, which I am coloring it in red right over here. So let's see. The point C is four to the left of the y-axis. So its reflection is going to be four to the right of the y-axis. So let me do it like this. So instead of being four to the left, we wanna go four to the right, so plus four. So where would that put our C prime? So our C prime would be right over there. And what would its coordinates be? Well, it would have the same y-coordinate, so C prime would have a y-coordinate of negative two. But what would its x-coordinate be? Well, instead of it being negative four, it gets flipped over the y-axis, so now it's gonna have a x-coordinate of positive four. So the coordinates here would be four comma negative two. Four comma negative two. You might've been able to do this in your head. Although, for me, even if I try to do it in my head, I would still have this visualization going on in my head. Negative four comma negative two. I'm sitting there in the third quadrant. If I'm flipping over the y-axis, my y-coordinate wouldn't change, but my x-coordinate would become the opposite and I would end up in the fourth quadrant, and that's exactly what happened. Y-coordinate did not change, but then my x-coordinate, since I'm flipping over the y-axis, it became the negative of this, so the opposite of negative four which is positive four.

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Reflecting points (video) | Reflections | Khan Academy

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Instructor] We're asked to plot the image of point A under a reflection across the line l. So we have our line l here, and so we wanna plot the image of here, we wanna plot the image of point A under a reflection across line l.

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Reflecting Points in the Coordinate Plane - Quiz

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Free gamified quizzes on every subject that students play in class and at home. Pick an existing quiz or create your own for review, formative assessment, and more.

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B, C, and D about point A. Then, slide the slider to see another alternative way to describe what it means to reflect any object (point, polygon, whatever) about a point. (Feel free to move points , B, C, and/or D anywhere you'd like at any time.)

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B, C, and D about point A . Then, slide the slider to see another alternative way to describe what it means to reflect any object (point, polygon, whatever) about a point. (Feel free to move points , B, C, and/or D anywhere you'd like at any time.)

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Joc

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Reflections are everywhere ... in mirrors, glass, and here in a lake.
... what do you notice ?

Every point is the same distance from the central line !
... and ...
The reflection has the same size as the original image.

The central line is called the Mirror Line:

Can A Mirror Line Be Vertical?

Yes. Here my dog "Flame" shows a Vertical Mirror Line (with a bit of photo editing).

You can try reflecting some shapes about different mirror lines here:

How Do I Do It Myself?

Just approach it step-by-step. For each corner of the shape:

1. Measure from the point to the mirror line (must hit the mirror line at a right angle)

2. Measure the same distance again on the other side and place a dot.

3. Then connect the new dots up!

Labels

It is common to label each corner with letters, and to use a little dash (called a Prime) to mark each corner of the reflected image.

Here the original is ABC and the reflected image is A'B'C'

Some Tricks

X-Axis

When the mirror line is the x-axis
we change each (x,y) into(x,−y)

Y-Axis

When the mirror line is the y-axis
we change each (x,y) into(−x,y)

Fold the Paper

And when all else fails, just fold the sheet of paper along the mirror line and then hold it up to the light !

6716, 6717, 3346, 3344, 3345, 3347, 5152, 5153, 841, 842

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Learn about reflection in mathematics: every point is the same distance from a central line.

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Symmetry Questions Collected From 11+ papers

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Symmetry - Topic wise seperated questions from one hundred 11+ Papers with detailed answers. Expected time to solve, similar questions of 11 Plus exam practice papers.