# Common Core State Standards for Mathematics

Grade 8 | Geometry

Understand congruence and similarity using physical models, transparencies, or geometry software.

Common Core Standards

Verify experimentally the properties of rotations, reflections, and translations:
-- a. Lines are taken to lines, and line segments to line segments of the same length.
-- b. Angles are taken to angles of the same measure.
-- c. Parallel lines are taken to parallel lines.

Understand congruence and similarity using physical models, transparencies, or geometry software. 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.

Describe the effect of dilations, translations, rotations and reflections on two-dimensional figures using coordinates.

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.

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.