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FINAL EXAM REVIEW. Chapter 4 Key Concepts. Chapter 4 Vocabulary. congruent figures corresponding parts equiangular Isosceles Δ legs base vertex angle base angles. median altitude perpendicular bisector CONGRUENCE METHODS: SSS SAS ASA AAS HL.
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FINAL EXAM REVIEW Chapter 4 Key Concepts
Chapter 4 Vocabulary congruent figures corresponding parts equiangular Isosceles Δ legs base vertex angle base angles median altitude perpendicular bisector CONGRUENCE METHODS: SSS SAS ASA AAS HL
Defn. of Congruent Triangles • Two triangles are congruent ( ) if and only if their vertices can be matched up so that the corresponding parts (angles and sides) of the triangles are congruent. ∆ ABC ∆ DEF ORDER MATTERS! 7 D A 7 7 E B 7 A D 7 F C 7 AB DE BC EF B C E F CA FD
SSS Postulate If three sides of one triangle are congruent to three sides of another triangle, then the triangles are congruent. S B A R C T ~ ABC = RST by SSS Post.
SAS Postulate If two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the triangles are congruent. F Q E P G R ~ EFG = PQR by SAS Post.
ASA Postulate If two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the triangles are congruent. M Y N Z L X ~ XYZ = LMN by ASA Post.
The AAS (Angle-Angle-Side) Theorem If two angles and a non-included side of one triangle are congruent to the corresponding parts of another triangle, then the triangles are congruent. B Y ABC XYZ C Z A X
The HL (Hypotenuse - Leg) Theorem If the hypotenuse and a leg of one right triangle are congruent to the corresponding parts of another right triangle, then the triangles are congruent. A X ABC XYZ Z B C Y
Summary of Ways to Prove Triangles Congruent Right triangles All triangles SSS Post SAS Post ASA Post AAS Thm HL Thm
The Isosceles Triangle Theorem If two sides of a triangle are congruent, then the angles opposite those sides are congruent. Iso. Thm.
Converse to Isosceles Triangle Theorem If two angles of a triangle are congruent, then the sides opposite those angles are congruent. Converse to Iso. Thm.
Corollaries • An equilateral triangle is also equiangular. • An equilateral triangle has three 60o angles. • The bisector of the vertex angle of an isosceles triangle is perpendicular to the base at its midpoint.
Median • A median of a triangle is a segment from a vertex to the midpoint of the opposite side. Each triangle has three medians. A A . A . . B C B C B C
Altitude • The perpendicular segment from a vertex to the line that contains the opposite side. A A A Acute Triangles C C C B B B Right Triangles A A A C C C B B B Obtuse Triangles C C C B B B A A A
Perpendicular Bisector • A line, ray, or segment that is perpendicular to a segment at its midpoint.
Theorem • If a point lies on the perpendicular bisector of a segment, then… the point is equidistant from the endpoints of the segment. . . . CONVERSE: If a point is equidistant from the endpoints of a segment, then… the point lies on the perpendicular bisector of the segment.
Theorem • If a point lies on the bisector of an angle then,… the point is equidistant from the sides of the angle. . CONVERSE: If a point is equidistant from the sides of an angle, then…..the point lies on the bisector of the angle.
Homework • Chapter 3-4 Review Olympics W/S • pg. 164 #1-9 (multiple choice)