Congruence
12 videos
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18
Geometry - What Is Congruence?
This video explains congruence in geometry, covering rigid transformations (translation, rotation, reflection) that preserve congruence and why dilations do not.
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17
Geometry - The 4 Triangle Congruence Criteria: SSS, SAS, ASA, AAS
Learn the four triangle congruence shortcuts: SSS, SAS, ASA, and AAS. Understand why AAA and SSA don't work for proving congruence.
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Geometry - Why SSA Doesn't Prove Congruence
Explains why SSA (Side-Side-Angle) doesn't prove triangle congruence, demonstrating the ambiguous case where two different triangles can share the same SSA measurements.
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Geometry - Determining If Triangles Are Congruent
Learn how to prove triangle congruence using SSS, SAS, ASA, and AAS patterns. Understand why order matters and why SSA doesn't work.
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Geometry - CPCTC: Corresponding Parts of Congruent Triangles
Learn how proving triangle congruence unlocks six facts: three pairs of equal sides and three pairs of equal angles through CPCTC (Corresponding Parts of Congruent Triangles are Congruent).
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Geometry - Finding Missing Angles with Congruent Triangles
Learn how to find a mystery angle in congruent triangles using angle sum and CPCTC. The letter order in congruence statements reveals corresponding parts.
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Geometry - Isosceles and Equilateral Triangle Properties
Learn about isosceles and equilateral triangles, their properties, and how equal sides create equal opposite angles. Discover why every equilateral triangle is also isosceles.
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Geometry - Finding Angles in Isosceles Triangles
Learn how to find missing angles in isosceles triangles using the equal base angles property and the 180-degree rule with a step-by-step example.
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Geometry - Writing Triangle Congruence Proofs
Learn how to write triangle congruence proofs step-by-step using givens, reflexive property, and SSS criterion. Includes a complete example with quadrilateral JKLM.
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Geometry - Parallelogram Properties from Congruence
Learn how to prove parallelogram properties using triangle congruence, alternate interior angles, and ASA to show opposite sides are equal and diagonals bisect each other.
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Geometry - Rhombus and Kite Diagonal Properties
Learn how diagonal properties of kites and rhombi create perpendicular relationships, and discover the simple area formula for a rhombus using its diagonals.
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Geometry - Geometric Constructions with Compass and Straightedge
Learn how to construct perpendicular and angle bisectors using only a compass and straightedge, explained through congruent triangles and SSS congruence.