Two Column Proofs – Proving a Parallelogram Is a Rhombus – Geometry

This geometry video tutorial explains how to prove if a parallelogram is also a rhombus using two column proofs. The theorems used in this includes the vertical angle theorem, the AAS triangle congruence postulate, CPCTC, definition of an angle bisector, and the base angle theorem for isosceles triangles.

Polygons:

Angles of Regular Polygons:

Quadrilaterals:

Parallelograms:

Rectangles – Special Quadrilaterals:

Isosceles Trapezoids:

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The Rhombus:

Kites:

Proving Parallelograms:

Proving a Quadrilateral Is a Kite:

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Proving Isosceles Trapezoids:

2 Column Proofs – Quadrilateral:

Skew Lines:

Points, Lines, Planes, & Segments:

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