- Jorge Cássio
Parallel Lines - Definition
Which pairs of lines are parallel? (use the "Show / Hide angle marks" box to help you)
Angles determined by parallel and transversal lines
In the previous structure, which pairs of angles are congruent?
In the previous structure, which of the following pairs of angles are supplementary?
Alternate Interior Angle Theorem (Alternate for the previous theorem)
Constructing a parallel line
Write an argument to justify the construction.
Exterior Angles of a Triangle
Triangle Exterior Angle Theorem
Interior angles of the triangle (source: https://www.geogebra.org/luisclaudio)
Move the selector "t". Also move the vertices of the triangle. What can you see?
Explain the previous property.