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#1 2015-11-05 13:36:59
- Lpravia020614
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- Registered: 2015-11-03
- Posts: 35
Dilation
Someone please help! I have tried to get the answers. My teacher has explained it to me but I still don't understand.
18. The translation of triangle BPU (-36, 20), (28, 16), and (8, 12) after a dilation is (9, -5), (-7, -4), and (-2, -3). What is the dilation? The scale factor is a fraction. The triangle is smaller than the original. The dilation is a contraction.
19. The translation of triangle GEP (-4, 10), (-9, -3), and (-6, 6) after a dilation is (-28, 70), (-63, -21), and (-42, 42). What is the dilation? The triangle is getting bigger than its original size.
20. The translation of triangle KTS (6, -36), (-60, 72), and (-54, -36) after a dilation is (1, -6), (-10, 12), and (-9, -6). What is the dilation? The triangle is getting smaller than the original, this is a contraction.
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#2 2015-11-05 20:16:17
- Bob
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- Registered: 2010-06-20
- Posts: 10,158
Re: Dilation
hi Lpravia020614
If the origin is the centre of the dilation (and it seems it is for these questions) then oldx times D = newx and similarly for the y coordinates. D is the scale factor of the dilation.
example. If the point is (9,12) and it dilates to (3,4) then 9D = 3 and 12D = 4. You can see that D=1/3
If you do an accurate plot on graph paper it will become clearer.
http://www.mathsisfun.com/geometry/resizing.html
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob 
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#3 2015-11-07 14:21:55
- Lpravia020614
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- Registered: 2015-11-03
- Posts: 35
Re: Dilation
Thank you! I finally got the answers right! Now I am stuck on proof, could you help ?
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#4 2015-11-07 15:15:54
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,158
Re: Dilation
Well done!
I'll try. What do you have to prove?
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
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