Question

Given:angle 1 = angle 2

If AC:BC = 3:5 and AB = 12, find DB.


A. 1.5

B. 4.5

C. 7.5

D. 12

Answer 1

I think that's it, I tried to do by similarity of triangles!
If you draw on a sheet is easier to understand

ac = 3
cb = 5
db = 12 - x
ad = x
looks like this:

ac / cb = ad / db
3/5 = x/12-x
36 -3x = 5x
-8x = -36 (-1)
x = 36/8
x = 4,5

But there is one, the value of dB = 12 dB then x = 12 to 4.5 = 7.5

Answer 2

so is it 7.5 or 4.5?

Answer 3

is 7.5 I had forgotten to decrease by 12

Answer 4

this proportion stuff is killing me. Do you have any tips?

Answer 5

Enough trains similarity rules of not very difficult triangle, so solve some exercises then it will with time taking the geito, you can always do so:

eg, a triangle has a 5 and ab = bc = 10 sides another triangle corresponding rules of similarity sides have xy = 10 x = yz. What did have to do is divide
By xy and ab equals bc division by yz, then solves the equation!
I find it easier to draw on a paper then you can understand, at least I do so! :)

Answer 6

Excuse the grammatical errors, I am translating by google! hehehe

Answer 7

your Spanish speaker?

Answer 8

No, Portuguese-BR! ;)

Answer 9

tu sere como quesh. lol jk can you help me with another problem?

Answer 10

quesh ?? o.O
lol yes, I can!

Answer 11

Given: 1 = 2

If AB = 10, AC = 6, and BC = 6, find AD:


5

10

15

Answer 12

I meant to say you smell like cheese in Portuguesa hehe

Answer 13

hmm .. kkkkk
I think this exercises is almost the same thing, but I found none of these values​​! Would not have the result 14? : s

Answer 14

i did like the one before.
AB=10 AC=6 BC=10 and then i made AD=10-x and DB=x
i setup the proportion like this. 6/6=10-x/x.
then i did 6(10-x)=6x
60-6x=6x
60=12x
x=5
10-5=5 does this make sense?

Answer 15

yes, yes sorry I think I did something wrong even!
the exercise said "Given: 1 = 2" then when I put equality, type:
6/6 = WHAT results in just 1 1 = 2 then replaces most ta think wrong. The only valid answer would be 5, could not find for the other values​​!

Answer 16

haha team work! how do you get your answers?

Answer 17

sorry, I did not understand! o.O know is the translation .... hehehe :/

Answer 18

oh okay you don't understand me? you are very smart. that is what i was trying to tell you

Answer 19

Oh yeah, thank you!
I'm actually not very smart! more physics, mathematics and chemistry, and the only study materials I like so do not know much! more thanks!!

Answer 20

i have difficulty with physics and mathametics! but i love English and history hehe

Answer 21

hehe I also like history, have more preferably in studying feudalism forward! lol

Answer 22

well i like American history lol. you live in America? or Portuguese?

Answer 23

I am Brazilian ... hehe!
  Always studied the history of north america in a superficial way, some revolutions and nothing else! Study enough history of Brazil, particularly in the late 18th century and early 19th ..

Answer 24

I live in Brazil!

Answer 25

then why do you speak Portuguese? lol

Answer 26

Portuguese is the official language of Brazil!

Answer 27

BTW, in the above two problems they are not similar triangles. It makes use of a property of angle bisectors. An angle bisector divides the opposite side in the same ratio as that of the other two sides. AC / BC = AD / BD

Answer 28

so the answers for the above problems are wrong? @ranga

Answer 29

yes, of Portugal is Portuguese and Brazilian Portuguese, the two languages ​​have hardly changed!

More if they are in the same proportion that allowed me to use a certain similarity triangle? can happen in this ratio not be applied in this fashion?

Answer 30

No, the answers are correct. But the property that is used is the property of angle bisector and not the properties of similar triangles.

Answer 31

oh ok thanks.

Answer 32

You are welcome.

Answer 33

hehehe, look I give erroneous theories, sorry. In the next exercise we know what to use! :)