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### Course: High school geometry>Unit 2

Lesson 5: Proofs with transformations

# Proofs with transformations

## Want to join the conversation?

• At , Sal talks about a bisector. What is a bisector?
• A bisector cuts something evenly in half.
• i understand what the video is saying, but the practice activity that comes next is completely different than the examples in the video, is there something i am missing?
• I had the same problem! I never learned any of the proof laws and rules so I am struggling to understand things like "Vertical angles are complimentary."
• Okay, so I'm going to be the stupid one here...
Even after watching this, I'm still REALLY confused about proofs. I think that they're overwhelming, so that makes it difficult to do my homework. Can someone please help me and explain this a little more? Thank you!
• From what I gather, A proof= a movement that shows undoubtedly based on the postulates of euclidian geometry that one statement is true.

for example, if you wanted to prove that a parallelogram had 2 axises of reflectional symmetry, you could reflect the parallelogram by both potential axises of symmetry, showing how the points map onto each other.

for better explanation, see: https://www.cs.sfu.ca/~ggbaker/zju/math/proof.html#:~:text=Proof%20%3A%20a%20valid%20argument%20that,from%20the%20more%20important%20one.
• At ~, shouldn't the second multiple choice said "If ∠AOC is rotated...", not "If Ray OA and Ray OC are rotated..."? Because you can't rotate points, rays, lines, or line segments due to them not having a vertex, right?
• Yes, you can rotate those around a point/origin, actually.
• - So this symbol ≅ means congruent?
• In general it means approximately and about, but in geometry it means congruent.
• What is "Theta''s and "Phi's" purpose, and where did the origin of the names come from?
• The names are from Greek: θ, π as I said above. Here, they are used as angle placeholders. Hope this helps!
• Hi, I would really like help with this...I've already completed my geometry course in high school and understood it, but my geometry doesn't do well on standardized tests so I've been taking this course. I just did the practice for proofs with transformations and it seems different from that of the video and rather confusing. I'm not getting it all. Can someone possibly be so kind as to help me? I don't understand the terminology of the practice, and I'm just getting all the answers wrong because I can't understand the questions. I haven't had much of a problem up until now. I'm just hoping for some assistance...
• ask me or tell me anything you need help with i got no issues with helping
(1 vote)
• what is fi
• I got yah Bro here yah go:)

the thing is (fi) like “fly,” is simply is an (( irrational number like pi (( p = 3.14159265358979… )), but one with many unusual mathematical properties. Unlike pi, which is a transcendental number, phi is the solution to a quadratic equation.