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Proof By Contradiction

Comments

  • #2
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    YeaaahFaoiSin wrote: »
    What proof is everyone learning for this? Does it have to be related to Geometry?

    Would this one be ok?

    http://educ.jmu.edu/~taalmala/235_2000post/235contradiction.pdf

    We did both the root of 2 is irrational and the geometry one in class to be covered in case they ask for a geometry one. That looks fine though anyway!


  • #3
    FaoiSin
    Registered Users, Registered Users 2 Posts: 789 ✭✭✭FaoiSin


    ChemHickey wrote: »
    We did both the root of 2 is irrational and the geometry one in class to be covered in case they ask for a geometry one. That looks fine though anyway!

    Sound :) Could you point me in the direction of a Geometry one? Just to be on the safe side!


  • #4
    K_1
    Closed Accounts Posts: 326 ✭✭K_1


    Anyone know what you say to explain proof by contradiction? i.e. the question that was in the 2012 sample? (6A)


  • #5
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    YeaaahFaoiSin wrote: »
    ChemHickey wrote: »
    We did both the root of 2 is irrational and the geometry one in class to be covered in case they ask for a geometry one. That looks fine though anyway!

    Sound :) Could you point me in the direction of a Geometry one? Just to be on the safe side!

    I don't have a link to it atm I'm on my phone but if you check up one of these on Google

    to show a tangent only touches a circle once
    or to show a tangent touches a circle at 90 degrees to the centre.

    i think it's the second one anyway.


  • #6
    Blink182rock
    Registered Users, Registered Users 2 Posts: 484 ✭✭Blink182rock


    K_1 wrote: »
    Anyone know what you say to explain proof by contradiction? i.e. the question that was in the 2012 sample? (6A)

    To show a proposition is true, assume its opposite is true and then show that leads to a concussion that is false!
    Thus, the original proposition is true because its opposite is false.
    (it is assumed that a proposition is either true or false)

    if that makes sense :)


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