# proving lines parallel

- Author:
- Mark Humphries

## Move the slider so that line g and line h are parallel.

How do you know that the two lines will be parallel?

## Move the slider so that lines g and h become parallel.

How do you know that lines g and h are parallel?

## Move the slider so that lines f and h become parallel.

How do you know that lines f and h are parallel?

## Move the slider so that lines f and h become parallel.

How do know that lines f and h will be parallel?