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Wednesday, February 16, 2011

hw #4-5 Dilations and the Coordinate Plane

Due Fri Feb 25
Make sure you do and understand hw #4-5
I will be checking the homework on Friday
and we will be MOVING ON!!
I expect questions on the blog if you do not understand something!

hw #4-5
Due Weds Feb 23
Read pg 187-88
pg 189 #1-14 All, #15,16,18-22
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10 comments:

  1. AnonymousFebruary 16, 2011 at 4:38 PM

    how do you do problem #4 and #5?

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  2. AnonymousFebruary 21, 2011 at 9:40 AM

    I dont know how to increase the figure scale factor for question 5 and 6?

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  3. Mr. ChamberlainFebruary 21, 2011 at 5:50 PM

    Not to worry, we'll go over both of these in class.

    #4 & 5 are difficult to explain in narrative, but I'll try. Take a look at the answer for #5 in the book and that might help.

    For #4, the triangle will "shrink" towards vertex C by a factor of 1/2, meaning that the lengths of all sides will be halved and C and C' will be the same point, while A' and B' will slide towards C.

    For #5, since B is the center of dilation, the new vertices of A' and C' will slide away from B and the lengths of the sides of the image figure will be twice that of the original figure. B and B' will be the same point.

    For #6 & 7, you need to know that the center of dilation is assumed to be the origin (0,0) unless otherwise stated (see bottom of page 187).

    For #6, since the scale factor is 2, everything is doubled. A' will be at (4,0) instead of (2,0) (twice as far away) and the lengths of each side of the image rectangle will also be doubled.

    Same idea for #7, except that A' will be i1/2 the distance, so it's coordinates will be (1,0) and the lengths of the sides will be half that of the original figure.

    Again, we will be reviewing in class.

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  4. Maggie JFebruary 22, 2011 at 7:53 PM

    I don't know how to get the scale factor for # 15 on page 190.
    -Maggie

    ReplyDelete
  5. AnonymousFebruary 23, 2011 at 4:21 PM

    What is the homework for today 2/23?

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  6. Mr. ChamberlainFebruary 23, 2011 at 5:18 PM

    For #15, try finding a common denominator and using improper fractions... that might help.

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  7. AnonymousFebruary 24, 2011 at 5:46 PM

    Mr chamberlain for problems 13 and 14 I'm having a little trouble.I tried graphing out the coordinates to visualize the dilation but is their a formula to make it easier How would I set up a proportion to find the solution.


    Kyle

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  8. AnonymousFebruary 24, 2011 at 6:47 PM

    Thanks Mr. Chamberlain that really helped. The answer was right there, it was easier than I thought.
    -Maggie

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  9. AnonymousFebruary 24, 2011 at 6:56 PM

    thank you for answering questions i didnt understand some of these as well

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  10. Mr. ChamberlainFebruary 24, 2011 at 7:11 PM

    For #12-14, you must remember the ASSUMPTION stated at the bottom of page 187... all dilations in the coordinate plane are assumed to "originate" from (0,0) - aka the "origin" unless stated otherwise.

    In #14, based on a scale factor of 1.5, any point in the original figure, such as (3,0) will transform (change or move) it's location to be 1.5 times further from the origin than it's original location.

    E (3,0) -> E'(4.5,0)
    F (0,-2) -> F' (0,-3)
    G (-3,1) -> G'(-4.5,1.5)
    H (2,3) -> H' (3,4.5)

    I see a pattern where you could apply a formula. Do you????

    ReplyDelete

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