The connection between concepts in geometry is very close, making some things need to be known to students before he learns the concept of tangent circles, including students must first understand the concept of circles and their properties, concepts of lines and the theorem of Pythagoras. If the initial concepts that are a prerequisite for a geometric concept are not yet understood, it can be ascertained that students are not able to understand the concept.
Learning to find tangent concepts in a circle will be meaningful if invited together (students) guided to find out the concept by linking the understanding of knowledge he has about the concept of circles, the concept of lines and the concept of the Pythagorean theorem. For simplicity, images can be used as visualizations.
