Proof: Basic Proportionality Theorem for Triangles | Geometry

[@SO111OO11]

You are a really good teacher Sir! I just wrote my board exam and this is EXACTLY what came in the exam. I remembered it so well i completed the whole proof in 5 mins 😂😂. Thank you so much for the video. I will definitely be keen to check on future lessons!

[@suggi6860]

Very much thank you!!.....I was so confused in this proof ...You are amazing

[@WrathofMath]

You're very welcome! I'm glad to hear it helped and let me know if you ever have any video requests!

[@zaini7255]

thank you sm!!!!!!!! the explanation was amazing and rlly easy to understand

[@WrathofMath]

Glad to help!

[@BornToThinkExpressively]

Beautiful, just beautiful 🥲

[@WrathofMath]

Thank you!

[@AbhishekRai-qo2fj]

Love from India sir

[@nolansharma9891]

Boards kaisa gya bhai

[@Gaelrenaultdu06]

Hello, could you prove the 3rd equality ? DE/BC = AE/EC ?

[@ganeshkanse1848]

Its gone very helpfull to me thanks 🙏

[@WrathofMath]

So glad it was helpful! Thanks for watching!

[@migfed]

Beautiful

[@WrathofMath]

Thank you!

[@rssl5500]

Hello I have a question I think the proof has a problem you drew altitude from point E to AD but what if there is an acute angle that is an gone bigger than 90 degrees then you can’t draw inner altitudes so this assumption is wrong

[@WrathofMath]

Thanks for watching and for your question! I just looked at the proof briefly to see your question, so I could be wrong - but I'm pretty sure we never use the assumption that the altitude EP falls inside of the triangle. What's important is that it intersects line AB, it's the distance from that line to point E, and this is the height of two of our triangles. By the line AB I mean if we were to continue segment AB infinitely in either direction to create a line. If angle A is obtuse, then like you say the altitude from E will fall outside of the triangle, but that doesn't break anything in the proof, it would just make us have a slightly uglier diagram. Hope that helps!

[@Z-eng0]

Well I think the proof doesn't care where exactly the altitude is drawn (even if it doesn't touch any of the named points at all) the only important thing is to show that the altitude connecting st. line AE and st. line AB is the same for both triangles, Which will always be inside triangle ABC either way (note: I tried making

[@krishorepalanati7980]

Thanks sir

[@WrathofMath]

No problem, thanks for watching and for the request!

[@jonathanmartinbenitez7427]

Thanks Lot !!!

[@WrathofMath]

My pleasure!

[@bohlalenchabeleng1370]

WOW!

[@phs-jr6yz]

This must be the first Math teacher who talks a lot, too much for an intro bro

[@VoidXD]

You just help me on subset thank you

[@WrathofMath]

Glad to hear it! Thanks for watching!