CHAPTER 2 Circles
Construct a circle of radius zero. . .
Although it is often an intermediate step, angle chasing is usually not enough to solve a problem completely. In this chapter, we develop some other fundamental tools involving circles.
2.1 Orientations of Similar Triangles You probably already know the similarity criterion for triangles. Similar triangles are useful because they let us convert angle information into lengths. This leads to the power of a point theorem, arguably the most common sets of similar triangles. In preparation for the upcoming section, we develop the notion of similar triangles that are similarly oriented and oppositely oriented. Here is how it works. Consider triangles ABC and XYZ. We say they are directly similar, or similar and similarly oriented,if