Triangle Sum Theorem

Triangle Sum Theorem

MAFS.8.G.1.5

By D-math Professor

​Warm-up (4 mins)

​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.

Multiple Choice

What is the sum of any triangle?

• 270 degrees

• 90 degrees

• 180 degrees

• 360 degrees

​What is the value of the missing angle?

​What is the value of the missing angle?

​The triangle sum theorem will require that we use angle relationships to solve for exterior angles as well. This includes; supplementary, complementary, vertical, alt. exterior, alt. interior, and corresponding angles.

​What is the value of the missing angle?

Open Ended

What relationship was used to solve the previous example?