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a bit stuck with ratios

hi im kinda confused how i would put this in ratio form

Screenshot_48.png


CD = (-3/2) AB

AB:CD
-3/2 : 1


sorry i just cant remember what id do
Reply 1
Avatar for mqb2766
mqb2766
21
Original post by anonymous230
hi im kinda confused how i would put this in ratio form

Screenshot_48.png


CD = (-3/2) AB

AB:CD
-3/2 : 1


sorry i just cant remember what id do

AB and CD are lengths so no negative sign.
also ratios are usually expressed in terms of integers.

You have the fraction
CD = 3/2AN
So multiply through to get integers and write as a ratio.
(edited 4 years ago)
Original post by mqb2766
AB and CD are lengths so no negative sign.
also ratios are usually expressed in terms of integers.

You have the fraction
CD = 3/2AN
So multiply through to get integers and write as a ratio.

CD = 3/2 AB

2 CD = 3 AB

so would it be CD:AB = 2:3

im not sure how they got CD:AB = 3:2
Reply 3
Avatar for mqb2766
mqb2766
21
Original post by anonymous230
CD = 3/2 AB

2 CD = 3 AB

so would it be CD:AB = 2:3

im not sure how they got CD:AB = 3:2

It's always like that. Of the total length.
CD is 3/5
AB is 2/5
So the ratio CD:AB is 3:2.

I find it easier to think in terms of fractions to get it the right way round.
(edited 4 years ago)
Original post by mqb2766
It's always like that. Of the total length.
CD is 3/5
AB is 2/5
So the ratio CD:AB is 3:2.

I find it easier to think in terms of fractions to get it the right way round.


but CD would be 2/5 not 3/5?
i get the 2:3 thing but i get it swapped around
Reply 5
Avatar for mqb2766
mqb2766
21
Original post by anonymous230
but CD would be 2/5 not 3/5?
i get the 2:3 thing but i get it swapped around

No CD is larger than AB as it's multiplied by 3/2.
Just remember it's the opposite way from what you first think.
(edited 4 years ago)
Reply 6
Avatar for hoosie
hoosie
8
If you are still not sure how to work out CD:AB
from 2CD = 3AB you could try replacing CD and AB with numbers that hold the equation true.
For example let CD = 6 and AB = 4.
It is true 2 × 6 = 3 × 4
Can you express 6:4 as a simpler ratio? (this is equivalent to ratio CD:AB)
If you are ever not sure if your answer is correct just plug in some numbers to check.
Original post by hoosie
If you are still not sure how to work out CD:AB
from 2CD = 3AB you could try replacing CD and AB with numbers that hold the equation true.
For example let CD = 6 and AB = 4.
It is true 2 × 6 = 3 × 4
Can you express 6:4 as a simpler ratio? (this is equivalent to ratio CD:AB)
If you are ever not sure if your answer is correct just plug in some numbers to check.

thank you very much it became much clearer after i replaced it with numbers!

Original post by mqb2766
No CD is larger than AB as it's multiplied by 3/2.
Just remember it's the opposite way from what you first think.

yehh i see now , thanks!

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