Question

Look at the figure below:

Triangle ABC is a right triangle with angle ABC equal to 90 degrees. The length of AC is 5 units, and the length of AB is 4 units. D is a point above C. Triangle ADC is a right triangle with angle DAC equal to 90 degrees and DC parallel to AB.

What is the length, in units, of segment CD?

8
9
6.25
7.25

Answer 1

Help again please

Answer 2

ba dum

Answer 3

Alright so for this question you are going to need to set up a proportion.

Our proportion will look something like this:
\[\frac{ AB }{ AC } = \frac{ AC }{ CD }\]

We already know the values for AB and AC so we will solve for CD:
\[\frac{ 4 }{ 5 } = \frac{ 5 }{ CD }\]

Can you solve the proportion from there?

Answer 4

Um-

Answer 5

yeah, I'm not going to lie I don't remember how to do this

Answer 6

its alright, it look harder than it seems, just substitute CD of x and solve it just like you would with a pre-algebra question

\[\frac{ 4 }{ 5 } = \frac{ 5 }{ x }\]

btw, when you are solving, you have to cross multiply. does that help?

Answer 7

are you confused?

Answer 8

So when it says 4/5 do I multiply both of those by the 5/x?

Answer 9

ok I'll draw it out for you

5 · 5 = ?
4 · x = ?

Answer 10

Alright also sorry for being so absent I keep getting called to do stuff

Answer 11

so 5 times 5 is 25 and um would 4 times x turn into 4x?

Answer 12

yep

Answer 13

yay, you got it, so now solve for x.

25 = 4x

Answer 14

does it say what x = to?

Answer 15

nevermind

Answer 16

no... we are solving for x

Answer 17

Um how do I solve for x again?

Answer 18

6.25

Answer 19

divide 25 by 4

Answer 20

divide both sides by 4

25/4 = 4x/4

Answer 21

25/4 is 6.25

Answer 22

you got it!

Answer 23

great job!! and 6.25 is one of your answer choices!

Answer 24

Oh nice

Answer 25

:D

Answer 26

yay