Bell Work 12/2, 12/3 Work the triangle congruency worksheet. Due in about 15 minutes. I will check for completion before we go over it. Be sure to work the back!

Outcomes I will be able to: 1) Prove that triangles are congruent by: SSS, SAS, ASA, AAS 2) Prove that corresponding parts of congruent triangles are congruent 3) Understand and use properties of special triangles(isosceles, equilateral, right)

Using Congruent Triangles What must we do first before we can prove the angles are congruent? How can we prove the triangles are congruent? ∆PQS ∆RQS, by SSS If the triangles are congruent, what do we know about their corresponding angles? Corresponding parts of congruent triangles are congruent

Example 1 Given Def of midpoint Def. of Vertical Angles By SAS CPCTC Alt. Interior Angles Converse

Example 2 Try this on your own. Be sure to mark what is given to us, and what we know from the picture before starting the proof.

Example 3 Given Reflexive Given LP is congruent NPCPCTC

Quick Practice Can we prove this parts of the triangle to be congruent? Why or why not 1) WX and ZA?2) NP and RS?

Parts of an Isosceles Triangle Base Angles Vertex Angle The angles at the base of an isosceles triangle The angle between the congruent sides of an isosceles triangle

Isosceles Triangles If two sides of a triangle are congruent then the angles opposite them are congruent If two angles of a triangle are congruent then the sides opposite them are congruent

Given CPCTC

Equilateral/Equiangular Triangles A

Example Find the value of x and y

Example Find the value of x and y

Hypotenuse-Leg (HL) Congruence

Practice