This topic examines the basic properties of circles, how to use Pythagorean theorem, triangle similarity and other properties to solve the side length, and how to express and discuss the properties of piecewise functions. Although the topics seem novel, it is difficult to find ideas, but careful observation of each topic is a regular basic test site, so it is a high-quality topic as a whole and worth practicing seriously. The answer/exercise/math /799635 is actually not too difficult, mainly because the idea is right.

Accept it, dear.