CCSS: Mathematics, CCSS: Grade 8, Geometry
8.G.A. Understand congruence and similarity using physical models, transparencies, or geometry software.
8.G.A. Understand congruence and similarity using physical models, transparencies, or geometry software.
- 8.G.A.1. Verify experimentally the properties of rotations, reflections, and translations:
- 8.G.A.1a. Lines are taken to lines, and line segments to line segments of the same length.
- 8.G.A.1b. Angles are taken to angles of the same measure.
- 8.G.A.1c. Parallel lines are taken to parallel lines.
- 8.G.A.2. Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent figures, describe a sequence that exhibits the congruence between them.
- 8.G.A.3. Describe the effect of dilations, translations, rotations, and reflections on two-dimensional figures using coordinates.
- 8.G.A.4. Understand that a two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations, and dilations; given two similar two-dimensional figures, describe a sequence that exhibits the similarity between them.
- 8.G.A.5. Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles.For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so.