All practice problems from the unit. Unit: Geo.3 Similarity (Geometry). Geo.3 Similarity In this unit, students use dilations and rigid transformations to justify triangle similarity theorems including the Angle-Angle Triangle Similarity Theorem. Students explicitly build on their work with congruence and rigid motions, establishing that triangles are similar by dilating them strategically. The unit balances a focus on proof with a focus on using similar triangles to find unknown side lengths and angle measurements. Read More Lessons Resources Assessments Lessons Properties of Dilations 1 Scale Drawings 2 Scale of the Solar System 3 Measuring Dilations 4 Dilating