Saturday, September 4, 2010

Writing a proof

Write a two column proof for one of  following. Remember, the left hand column is statements and the right hand column is reasons.  Make sure the steps are in a logical order.  Before you start, make sure you draw and label a diagram and try to "prove" it before you write your proof.   Start with the givens, put any postulates, definitions, etc.. that might apply, have the "prove" as a goal.  Remember, this is a learning experience! Take your time and do the best you can. 

Last name starts with A-L? Do this one!
Given= C is on segment on DE, DC=x, CE=3X, and DE=16.
Prove:x=4.


Challenge: What additional statements/reasons would you add on to prove 12=CE?

Last name starts with M-Z? Do this one!
Given B is in the interior of <CAR, m<CAB=x, m<BAR=6x, and m<CAR=91.
Prove: x=13.

Challenge: What additional statements/reasons would you add on to prove that 78=m<BAR?

2 comments:

  1. <CAR, m<CAB=x, m<BAR=6x, and <CAR=91 Given
    <CAB+<BAR=<CAR A.A.P
    x+6x=91 Substitution
    7x/7=91/7 Addition
    x=13 Division

    <BAR=6x Given
    6(13) Substitution
    78 Multiplication

    ReplyDelete
  2. C is on segment
    DE, DC=x, CE=3x,
    and DE=16 Given
    DC+CE=DE Segment Addiction Postulate
    (x)+(3x)=(16) Substitution Property
    4x=16 Addition
    x=4 Division Property
    CE=3(4) Substitution Property
    CE=12 Multiplication

    ReplyDelete