Triangle Congruence and Properties

Teacher Nancy introduces a lesson on triangle congruence for grade 8 mathematics. The video covers properties of triangle congruence, including reflexive, symmetric, and transitive properties. It provides examples and proofs using two column proofs, focusing on congruence postulates like ASA, SSS, and SAS. The lesson concludes with practice activities for students to apply their learning.

What should you prepare before starting the lesson?

• A textbook

• A self-learning module

• A calculator

• A geometry set

What is the definition of congruent triangles?

• Triangles with equal sides

• Triangles with equal angles

• Triangles with the same shape and size

• Triangles with parallel sides

Which property states that a triangle is congruent to itself?

• Associative

• Reflexive

• Transitive

• Symmetric

Which congruence postulate is not valid?

• ASA

• SSS

• SAS

• SSA

In Example 1, which postulate is used to prove triangle congruence?

• ASA

• AAS

• SSS

• SAS

What is the reason for angles being congruent when two parallel lines are cut by a transversal?

• Supplementary angles are congruent

• Vertical angles are congruent

• Alternate interior angles are congruent

• Corresponding angles are congruent

In Example 2, what is the common side in triangles STL and SEL?

• SL

• SE

• LE

• ST

Which property is used to prove that side SL is congruent to itself?

• Symmetric

• Transitive

• Reflexive

• Substitution

In Example 3, what is the definition of a perpendicular bisector?

• A line that divides an angle into two equal parts

• A line that divides a segment into two equal parts and forms right angles

• A line that intersects another line at any angle

• A line that is parallel to another line

Which congruence property is used in Example 3 to prove triangle congruence?

• ASA

• SSS

• AAS

• LL