M.2HS.43
Prove theorems about triangles. Theorems include: measures of interior angles of a triangle sum to 180°; base angles of isosceles triangles are congruent; the segment joining midpoints of two sides of a triangle is parallel to the third side and half the length; the medians of a triangle meet at a point.
Khan Academy ResourcesAngle-angle triangle similarity criterionTriangle congruence reviewProve theorems using similarityJustify triangle congruenceTriangle similarity postulates/criteriaIntro to triangle similarityIntro to angle bisector theoremProving the SAS triangle congruence criterion using transformationsProof: Parallel lines divide triangle sides proportionallyProving the SSS triangle congruence criterion using transformationsProving the ASA and AAS triangle congruence criteria using transformations

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