There are many ways of introducing mathematics. Students are invited together to analyze from the picture to find the long concept of internal alliance tangents. Thus more impressive students to understand and memorize the formula because it analyzes itself how the circle tangent length ep formula is obtained. The Mathematics Learning Change Expected. A teacher should not only teach by announcing (telling) or just for comprehension (understanding), but the teachers are required also to facilitate the students to think that they can be students are able to study independently (independent learners), forward-thinking, and creative.