Geometry Help: Reflections

[rachelmaddie]

I need these concepts explained.

 

[tkhunny]

It is explained in the text. Is here a particular problem you are working on?

 

[rachelmaddie]

It is explained in the text. Is here a particular problem you are working on?

No, that is the only explanation.

 

[Dr.Peterson]

So, what aspect of the book's explanation do you need help understanding? We need some sort of handle by which to grasp your need, so we don't just restate it in yet another way that doesn't help you.

 

[rachelmaddie]

So, what aspect of the book's explanation do you need help understanding? We need some sort of handle by which to grasp your need, so we don't just restate it in yet another way that doesn't help you.

I do not understand how the distance was found or how to write the composition in the first picture.

 

[rachelmaddie]

In the second picture, I do not understand how the angle of rotation was found.

 

[tkhunny]

Reflections, by definition, are the same distance from the line of reflection.

 

[Dr.Peterson]

The key idea in working out the angle is that the angle on one side of the line is equal to the angle on the other (by congruent triangles, since the distances from the line are equal as tk said.)

And the composition just means "do the second transformation mentioned, then do the first to the result". So here it says "reflect over line l, then over line m".

 

[rachelmaddie]

Reflections, by definition, are the same distance from the line of reflection.

So, it would be 2(70) = 140

 

[Harry_the_cat]

Yes that's correct.