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:

_________________________________
The Rhombus:

Kites:

Proving Parallelograms:

Proving a Quadrilateral Is a Kite:

__________________________________
Proving Isosceles Trapezoids:

2 Column Proofs - Quadrilateral:

Skew Lines:

Points, Lines, Planes, & Segments:

_______________________________________
Final Exams and Video Playlists:

Full-Length Videos and Worksheets:

[zelda]

Yay! In the state test last year, I hadn't been in Geometry yet, and I had to prove a shape was a rhombus. I had no clue how to do it, and I was unhappy. I skipped the question, already low on time. This year, in Geometry, we never learned how to prove a shape was a shape! We took a break from proofs in this unit. Everyone else was happy, but I was not because I wanted that skill in my arsenal. I asked my teacher about it, and he didn't explain it very much. This video has satisfied me, so I thank you.

[arijitdas]

Angle BEA is rt. angle, not angle BAE.

[georgesadler]

MR. Organic Chemistry Tutor, thank you for another incredible video/lecture on Two Column Proofs/Proving a Parallelogram Is a Rhombus. These two column proofs continue to be problematic, however repetition and memorization will also help with the theory in Geometry.

[al.x.s]

When proving triangles are congruent, you have three methods:
Side - Angle - Side
Angle - Side - Angle
Side - Side - Side

If you're doing the method A.S.A., then you have to choose an common side between the two angles...

In the first example he wrote, he proved that *triangle AEB is congruent to triangle DEC*.. but the angles he chose did not have a common side.. so from how I see it I feel like the statements he wrote in the first example were wrong..

[sasifrancism.]

This is exactly on my gf's homework lmao

Edit: Btw, just kidding.

[kunalkapur]

He probably meant for it to be there since def on perp visector

[judelyntana]

how angle BAE becomes right angle? sir it should be angle BEA in 5:50. :)

[ravpqyi]

i just need to copy this answers😎i know BAE is wrong, it should be BEA, (the statement on my modules is also wrong)

[RaniRani-zttr]

this is really well explained but there are mistakes

[wyptlgv]

A parallelogram is not a rhombus but a rhombus is a parallelogram

[yoyoz]

bro u deserve a sub ! u saved my life BRO THANK YOU SO MUCH

[jeremynavarro]

im bout to kms i still do not understand any of this proofs bs

[PubicGore]

A parallelogram is a rhombus if and only if the parallelogram is a rhombus. The video title should be "Two Column Proofs - Proving a Rhombus is a Parallelogram - Geometry."