HS.G.4.e

Prove and apply geometric properties and theorems regarding triangles, congruence, and similarity using deductive reasoning.

Example Problems
Could be the side lengths of a triangle?
Could 8, 46, and 42 be the side lengths of a triangle?
Could be the side lengths of a triangle?
Khan Academy Resources
Triangle similarity reviewAngle-angle triangle similarity criterionTriangle congruence reviewDetermine congruent trianglesFind angles in congruent trianglesSolve triangles: angle bisector theoremDetermine similar triangles: AnglesDetermine similar triangles: SSSSolve similar triangles (basic)Solve similar triangles (advanced)Prove theorems using similarityUse similar trianglesProve triangle similarityJustify triangle congruenceUse ratios in right trianglesProve triangle propertiesProve triangle congruenceCorresponding parts of congruent triangles are congruentTriangle congruence postulates/criteriaDetermining congruent trianglesWhy SSA isn't a congruence postulate/criterionGeometry proof problem: congruent segmentsProofs concerning isosceles trianglesProofs concerning equilateral trianglesCorresponding angles in congruent trianglesTriangle similarity postulates/criteriaSolving similar trianglesIntro to triangle similarityDetermining similar trianglesSolving similar triangles: same side plays different rolesChallenging similarity problemUsing similar & congruent trianglesIntro to angle bisector theoremUsing the angle bisector theoremExploring medial trianglesProving the SAS triangle congruence criterion using transformationsProving triangle medians intersect at a pointUsing similarity to estimate ratio between side lengthsProof: Parallel lines divide triangle sides proportionallyProving the SSS triangle congruence criterion using transformationsCalculating angle measures to verify congruenceGeometry word problem: Earth & Moon radiiGeometry word problem: a perfect pool shotDilating triangles: find the errorProving the ASA and AAS triangle congruence criteria using transformationsProving triangle congruenceGeometry word problem: the golden ratio
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