Grade Level/ Course : 8th Grade
Standard
8.G.5 Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles
with code: 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 three angles appear to form a line, and give an
argument in terms of transversals why this is so.
Domain
Cluster:
Geometry
Understand congruence and similarity using physical models, transparencies, or geometry software.
Type: _____Knowledge
__X__Reasoning
Knowledge Targets
Define similar triangles
Define and identify transversals
______Performance Skill
Reasoning Targets
Justify that the sum of interior angles equals
180. (For example, arrange three copies of
the same triangle so that the three angles
appear to form a line.)
_____Product
Performance Skills Targets
Product Targets
Identify angles created when
parallel line is cut by transversal Justify that the exterior angle of a triangle is
(alternate interior, alternate
equal to the sum of the two remote interior
exterior, corresponding,
angles.
vertical, adjacent, etc.)
Use Angle-Angle Criterion to prove similarity
among triangles. (Give an argument in terms
of transversals why this is so.)
Copyright © 2011 Kentucky Department of Education
The content of this document constitutes original works of authorship owned by the Kentucky Department of Education (KDE) and may not be reproduced without
the express, written permission of the KDE.
Make sense of
problems and
persevere in
solving them.
Reason
abstractly and
quantitatively.
Construct viable
arguments and
critique the
reasoning of
others.
Model with
mathematics.
Use appropriate
tools
strategically.
Attend to
precision.
Look for and
make use of
structure.
Look for and
express
regularity in
repeated
reasoning.
Copyright © 2011 Kentucky Department of Education
The content of this document constitutes original works of authorship owned by the Kentucky Department of Education (KDE) and may not be reproduced without
the express, written permission of the KDE.