Magic Geometry Construction | CMI Entrance 2022 B1 Problem, Idea and Solution| Math Olympiad

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  • Опубліковано 13 січ 2025

КОМЕНТАРІ • 135

  • @pramodk9760
    @pramodk9760 2 роки тому +7

    HI, can't we directly use Menalaus Theorem? Beautiful construction, by the way. Thanks!

    • @mayur_krishna_devotee
      @mayur_krishna_devotee 2 роки тому +2

      Yes we can, in fact that's how even I did in the exam

    • @namantenguriya
      @namantenguriya 2 роки тому

      @@mayur_krishna_devotee have u proved then, how lengthy the proof was?

    • @mayur_krishna_devotee
      @mayur_krishna_devotee 2 роки тому +2

      @@namantenguriyaYes, I could complete it, wasn't very lengthy, just one page along with diagram.

    • @rajkumarlakhmani3911
      @rajkumarlakhmani3911 2 роки тому +1

      @@mayur_krishna_devotee how many were you able to solve? I felt the paper to be on the tougher side this year. Like I was getting around 5/6 problems on an average, correct in my previous year attempts but this year, it felt like a disaster. I was just able to solve B1, B2, B5 completely and B3 partially. And I have no idea of how wrong I might have been in my Part A. Fingers crossed

    • @mayur_krishna_devotee
      @mayur_krishna_devotee 2 роки тому +2

      @@rajkumarlakhmani3911 This year, yes it was much harder, I could do B1,B5(i), B6 (i),(ii) and wrote B5(ii) in a hurry. Part A was something to be very careful about, need to hope for the best

  • @swastikadey256
    @swastikadey256 2 роки тому +5

    By menelau's theorem in triangle XYZ using transversal RPQ, ZQ/YQ*YR/XR*XP/PZ =1,
    So, k*XP/XR*(XY+XR) /(PW+WZ) =1,
    k*XP/XR*(XY+XR)/(XP+XY)k=1,
    XP(XY+XR)= XR(XY +XP),
    XY(XP-XR) =0,
    XP=XR, as XY can not be 0,
    Is my solution correct? I did it in this way

  • @namantenguriya
    @namantenguriya 2 роки тому +3

    I always wonder in geometry, how someone can be as able to do such perfect constructions... Maybe lots of practice. And it's what is most important in geometry problems.
    I tried it very hard in cmi x'm, do some construction, Menelaus thm & all but nothing was satisfactory.

  • @asifhossain566
    @asifhossain566 2 роки тому +2

    Beautiful explanation sir ❤️❤️❤️❤️❤️❤️❤️❤️

    • @Cheenta
      @Cheenta  2 роки тому

      Thank you for watching.

  • @meghnachaudhury8013
    @meghnachaudhury8013 Рік тому

    Beautiful solution!
    Thank you.

  • @vineetjain3172
    @vineetjain3172 2 роки тому +1

    I give cmi entrance exam I solved 29 questions in part a and 2 question in part b good pair and square cutting wala. What should I expect?

  • @SDB_Safal_Math_1729
    @SDB_Safal_Math_1729 2 роки тому +2

    Excellent!!!

    • @Cheenta
      @Cheenta  2 роки тому

      Glad you like it!

  • @sajaltuley1578
    @sajaltuley1578 2 роки тому +3

    Around how many marks one should get in part B? I was also to solve only one question r^2+s^3 wala

    • @rajkumarlakhmani3911
      @rajkumarlakhmani3911 2 роки тому

      Tell me about your approach for the second part of that question. That took a lot of brainstorming from my side

    • @sajaltuley1578
      @sajaltuley1578 2 роки тому +1

      @@rajkumarlakhmani3911 differentiate x^3-x^2 you will get 0 and 2/3 as its roots . Now good pairs can only exists between f(2/3) to f(0) because only between this part function is many one. So largest such l is (0, other point where its value is f(0) i.e 1) and smallest such s is (2/3, other point where its value is f(2/3) i.e -1/3) so l=1 and s =-1/3.

    • @mayur_krishna_devotee
      @mayur_krishna_devotee 2 роки тому +1

      @@sajaltuley1578 Nice, I followed the exact same approach in the exam.

    • @rajkumarlakhmani3911
      @rajkumarlakhmani3911 2 роки тому

      @@sajaltuley1578 that's the easier part. I specifically asked for the second part of the question that required us to prove that there are infinite *rational* good pairs.

    • @sajaltuley1578
      @sajaltuley1578 2 роки тому +1

      @@rajkumarlakhmani3911 the function is many one in infinite rational points that's only what I wrote. It's many one in an interval not at discrete points.

  • @subhranildeb2462
    @subhranildeb2462 Рік тому +1

    I want to admit online classes for my chaild who is in class eleven, and he is a math lovers, but can't enough study in agartala, plz help me to the right way to reach his goal.

    • @Cheenta
      @Cheenta  Рік тому

      You may apply at cheenta.com

  • @Aman_iitbh
    @Aman_iitbh 2 роки тому +1

    nyyc

  • @milindpatt4201
    @milindpatt4201 2 роки тому +1

    what could be the expected cutoff Part A and (Part A+Part B)

    • @rajkumarlakhmani3911
      @rajkumarlakhmani3911 2 роки тому +2

      My estimation for part A lies around 17-18 as difficulty was similar to previous years and total around 52-55

    • @milindpatt4201
      @milindpatt4201 2 роки тому

      @@rajkumarlakhmani3911 btw how much marks would i get in part B , i did B3 , B5 (i) i took f(x) = x^3-x^2 diff and showed that there exists no sol in -inf to 0 ) U ( 2/3 , inf) and left there and (ii) just wrote the hint and did some bullshit , B6 (i) showed that either x^2+x-1 can show atmost one sol when x^2+x-1 =p or atmost 1 when p/x^+x-1 ( didnt prove this part just stated it ) , same thing tried in (ii) , i wont clear the cutoff anyways but any rough guess of my marks

    • @rajkumarlakhmani3911
      @rajkumarlakhmani3911 2 роки тому

      @@milindpatt4201

    • @rajsingh8372
      @rajsingh8372 2 роки тому +2

      @@rajkumarlakhmani3911 previous year paper was easy as compared to this year paper so cut off might be around 40-44

    • @rajkumarlakhmani3911
      @rajkumarlakhmani3911 2 роки тому

      @@rajsingh8372 I really don't have any idea. Mr. Balasundar says it'd be around 58. My guess is 52

  • @sohamgupta5506
    @sohamgupta5506 2 роки тому +3

    THIS IS EASY BY MENELAUS THEORUM!!!