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Mathematics 8 Online
gokrazy223:

In the figure below, segment DE is parallel to segment BC and segment EF is parallel to AB: The figure shows triangle ABC with segments DE and DF. Point D is on side AB, point E is on side AC, and point F is on side BC. Segment AD is 16, segment AE is 24, segment EC is 36, and segment FC is 27. Which statement can be proved true using the given theorem? Segment BD = 32 Segment BD = 36 Segment BF = 15 Segment BF = 18

gokrazy223:

AZ:

So when we have a line that is parallel to one side in a triangle, then that means it divides the other two sides proportionally

AZ:

|dw:1614194986207:dw| This means that since DE is parallel to side BC we get \(\dfrac{AD}{AB} = \dfrac{AE}{AC}\) or also \(\dfrac{AD}{DB} = \dfrac{AE}{EC}\) and since we also have side EF parallel to AB, we get \(\dfrac{AE}{AC} = \dfrac{BF}{BC}\) or \(\dfrac{AE}{EC} = \dfrac{BF}{FC}\)

gokrazy223:

@AZ

gokrazy223:

what does that mean

AZ:

The sides are proportional. The two letters just means that line between those two points

AZ:

So let's just use one of these \( \dfrac{AD}{DB} = \dfrac{AE}{EC}\) From your image, you can see that AD = 16 DB = ?? AE = 24 EC = 36 Can you plug it in and solve for DB?

gokrazy223:

ill try

AZ:

just replace it with the numbers and in place of DB, you can use `x` and then we solve for x :)

gokrazy223:

|dw:1614195598567:dw|

AZ:

Good! Let's just put an x there and solve for it |dw:1614195732807:dw|

gokrazy223:

what would i have to do to find X

AZ:

oo of course we would cross multiply

1 attachment
AZ:

so when we do that, we get 16 * 36 = x * 24 can you solve for x now?

gokrazy223:

i got 76

gokrazy223:

something isnt right

AZ:

mhmm try again what is 16*36 = ? and then divide by 24

gokrazy223:

when i do that i get 72 and 24 can go into 72

AZ:

I'm not sure how you're getting 72 or 76 Let's simplify the numbers first, shall we?

AZ:

|dw:1614196091567:dw|

AZ:

I just simplified the fraction so now what is 3 * 16 = 2 * x

gokrazy223:

im doing my math wrong i got zero

AZ:

okay okay, step by step just pull out the calculator what is 16 * 3 = ?

gokrazy223:

48

AZ:

now divide by 2 48/2 = ?

gokrazy223:

24

AZ:

so we get x = 24 and we said x was the line segment BD and since that isn't an answer choice that means we have more work to do and we have to figure out what line segment BF is

gokrazy223:

oh lord

AZ:

I know right?!

gokrazy223:

math is alot

AZ:

So from the proportions I wrote earlier, we have to use this one now \(\dfrac{AE}{EC} = \dfrac{BF}{FC}\)

AZ:

so now we're solving for BF (because the two remaining answer choices and that's also the only side we don't know yet) From your main image AE = 24 EC = 36 BF = ?? FC = 27 so can you carry it away from here now? o:

gokrazy223:

@AZ

gokrazy223:

it it 18

AZ:

You got it!

gokrazy223:

i had too look back at everthing srry

AZ:

That's fine! I'm glad you finally got it :)

gokrazy223:

thank you

AZ:

You're welcome!

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