Question

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

8

9

6.25

7.25

Answer 1

i did the pythagorean theorem for the small triangle and got 3 for segment BC

Answer 2

lol..am i on the right path..? XD

Answer 3

is this trigonometry ?

Answer 4

only pytagoras won't help.
you'll need trigonometry

Answer 5

rats..no it's geometry

Answer 6

terenz ig getting a better idea, i guess

Answer 7

ok :) thanks @hartnn

Answer 8

AB and CD are parallel, we ought to use this fact.

Answer 9

Similar triangles.

Answer 10

for your convenience guys :)

Answer 11

oh, yeah...how could i not think of similarity.
you know what that is ?

Answer 12

ABC is similar to ADC. Equiangular.

Answer 13

@Azteck ' s idea is best methinks
I thought of trig at first, too, @hartnn , unfortunately :(

Answer 14

oh, wait....they are not similar i think

Answer 15

Now build up on it, how can you show that they are similar?

Answer 16

They are, @hartnn :)

Answer 17

Use trig to find BC and you're done.

Answer 18

pythagoras*

Answer 19

oh, yes, i just said "AB and CD are parallel"
so, yes, they are similar

Answer 20

@irishchelsc ar you catching u ?

Answer 21

*up

Answer 22

Okay, @irishchelsc
getting seasick yet? :)
Want me to walk you through it?

Answer 23

y'all are going really fast...

Answer 24

yes please @terenzreignz :)

Answer 25

Okay... what can you say about these two angles:

Answer 26

Remembering of course that AB is parallel to CD

Answer 27

they are alternate interior angles

Answer 28

lol. right.?

Answer 29

And therefore..? :)
You're right, but since they are alternate interior angles (of a pair of parallel lines), they are...?

Answer 30

vertical....too....?

Answer 31

ehhh...
Alternate interior angles are congruent :)