Teacher presentation materials. Unit: Geo.7 Circles (Geometry). Geo.7 Circles In this unit, students analyze relationships between segments and angles in circles, which leads to the construction of inscribed and circumscribed circles of triangles. Students solve problems involving arc length and sector area, and they use the similarity of all circles and ideas of arc length to develop the concept of radian measure for angles. Read More Lessons Resources Assessments Lessons Lines, Angles, and Circles 1 Lines, Angles, and Curves 2 Inscribed Angles 3 Tangent Lines Polygons and Circles 4 Quadrilaterals in Circles 5 Triangles in Circles 6 A Special Point 7 Circ