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Lesson Plan

Understand the relationships between angles and sides of an isosceles triangle by constructing triangles and using triangle inequalities

teaches Common Core State Standards CCSS.Math.Content.HSG-CO.C.10
teaches Common Core State Standards CCSS.Math.Practice.MP3
teaches Common Core State Standards CCSS.Math.Practice.MP8
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Big Ideas: Students will be able to apply the isosceles base angle theorem to solve problems. Students will be able to construct isosceles triangles. Students will be learning about the base angle theorem of isosceles triangles. Students will use that theorem to solve problems including designing a house with gables. Students will use what they have learned about constructing congruent segments and congruent angles, so this lesson should be taught after those topics have been covered. Students will be learning about proving triangles are congruent by using SSS, SAS, ASA, AAS in the next unit and can use SAS to prove that the base angles of an isosceles triangle are congruent. Vocabulary: base of an isosceles triangle, vertex of an isosceles triangle, legs of an isosceles triangle, base angles, vertex angle Special Materials: Protractor Compass Straightedge
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