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Chapter 5 . 5-6 inequalities in two triangles. Objectives. Apply inequalities in two triangles. Inequalities theorems. Example 1A: Using the Hinge Theorem and Its Converse . Compare m BAC and m DAC . Compare the side lengths in ∆ ABC and ∆ ADC .
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Chapter 5 5-6 inequalities in two triangles
Objectives • Apply inequalities in two triangles.
Example 1A: Using the Hinge Theorem and Its Converse • Compare mBACand mDAC. • Compare the side lengths in ∆ABC and ∆ADC. • AB = AD AC = AC BC > DC • By the Converse of the Hinge Theorem, mBAC > mDAC.
Example • Compare EF and FG. Compare the sides and angles in ∆EFH angles in ∆GFH. mGHF = 180° – 82° = 98° EH = GH FH = FH mEHF > mGHF By the Hinge Theorem, EF < GF
Example • Compare mEGHand mEGF.
Application • John and Luke leave school at the same time. John rides his bike 3 blocks west and then 4 blocks north. Luke rides 4 blocks east and then 3 blocks at a bearing of N 10º E. Who is farther from school? Explain.
solution • The distances of 3 blocks and 4 blocks are the same in both triangles. • The angle formed by John’s route (90º) is smaller than the angle formed by Luke’s route (100º). So Luke is farther from school than John by the Hinge Theorem.
Writing Proofs • Write a two-column proof. • Given: Prove: AB > CB
solution 1. Given 2. Reflex. Prop. of 3. Hinge Thm.
Example • Write a two-column proof. • Given: C is the midpoint of BD. • m1 = m2 • m3 > m4 • Prove: AB > ED
1. Given 1.C is the mdpt. of BD m3 > m4, m1 = m2 2. Def. of Midpoint 3.1 2 3. Def. of s 4. Conv. of Isoc. ∆ Thm. 5.AB > ED 5. Hinge Thm.
Student Guided Practice • Do problems 1-3 in your book page 355 • Do worksheet
Homework • DO problems 9-12 and 16 in your book page 355 and 356
Closure • Today we learned about hinge theorem and its converse • Next class we are going to learned about Pythagorean theorem