Reflections review. Math Basic geometry Transformations, congruence, and similarity Reflections. So this is going to be our C here.

Reflections: How to reflect a point

Now C prime would have the same X coordinate but instead of being four units below the X axis, it will be four units above the X axis. So let's make this right over here A, A prime. When you reflect a point across the x -axis, the x- coordinate remains the same, but the y -coordinate is transformed into its opposite its sign is changed. Imagine a straight line connecting A to A' where the origin is the midpoint of the segment.

Reflections in the coordinate plane: When we're talking about transformations, there are 4 different types one of which is a reflection. What this one does, it takes every x coordinate and then makes that into a y coordinate and does the same for your y coordinates, every y coordinate becomes an x coordinate so if we have a, our a since we have a prime and a double prime our a triple prime is going to be at 5, 3 so what I'm going to do is I'm going to write 3, 5 right here.

And what's interesting about this example is that, the original quadrilateral is on top of the X axis.

Problem 2 What is the image of point A 31,1 after reflecting it across the x-axis. So, its image, A prime we could say, would be four units below the X axis. Next Unit Area.

R is an invariant point in the above. Video transcript - [Instructor] We're asked to plot the image of quadrilateral ABCD so that's this blue quadrilateral here. What is Reflection? Now let's make this our C.

Reflecting shapes

The first one is xy is mapped onto -x, y. This one when you keep x the same and take the opposite of y you know that's a reflection over the x axis and last when you switch the x's and y's that will reflect it over line y equals x.

And this bottom part of the quadrilateral gets reflected above it. All Geometry videos Unit Transformations. Place the sharp point of a compass at A and draw two arcs intersecting the line XY.

Thank you for watching the video. If the axis of reflection is not on the grid lines, we will need to use a compass to construct the image.