Theorem: What is the Euclidean Theorem or Postulate we are applying to create this parallel line?

Here are some examples.
1. If two lines are cut by a transversal and a pair of corresponding angles are congruent, then the lines are parallel.
2. If two lines are cut by transversal and a pair of alternate interior angles are congruent, then the lines are parallel.
3. Two lnes parallel to a third line are parallel to each other.
4. Given a line and a point not on the line, there exists one and only one line parallel to the given line.

1. Open your document in Sketchpad.

2. Select the point tool.

3. Put a point anywhere on your document, except on the horizontal line. In other words, create a point not on the line.

4. Select the selection tool.

5. Select the horizontal line and the point.
> Construct
> Parallel Line


Now you have a pair of parallel lines.