# Question Video: Determining the Line of Reflection Mathematics • 8th Grade

โณ๐ต๐ธ๐น is the image of โณ๐ต๐ท๐น by reflection across ๏ผฟ.

01:19

### Video Transcript

Triangle ๐ต๐ธ๐น is the image of triangle ๐ต๐ท๐น by reflection across what.

To start, letโs think what possible thing we could be writing for our missing value. Is it, for example, a shape or a line or a point? Well, letโs recall that if we wanted to describe a reflection, we would first need to state what object is being reflected. And then, we would need to say the line of reflection.

In our question, triangle ๐ต๐ท๐น is the object thatโs being reflected. And therefore, our missing word or description must be the line of reflection. So weโre told that triangle ๐ต๐ธ๐น is the image of triangle ๐ต๐ท๐น. We can see that point ๐ธ is a reflection of point ๐ท. And we can see that point ๐น is the image of itself, and point ๐ต is also the image of itself.

This means that both these two points must lie on the line of reflection. Therefore, our line of reflection is the line ๐น๐ต. So we have triangle ๐ต๐ธ๐น is the image of triangle ๐ต๐ท๐น by reflection across the line ๐น๐ต.