Question

Triangle ABC is shown below.
Triangle ABC; line passes through points D, B, and E
Given: ∆ABC

Prove: All three angles of ∆ABC add up to 180°.

The flow chart with missing reason proves the measures of the interior angles of ∆ABC total 180°.

Which reason can be used to fill in the numbered blank space?

Associative Property of Addition

Triangle Exterior Angle Theorem

Angle Addition Postulate

Commutative Property of Addition

http://assets.openstudy.com/updates/attachments/4fc63cc2e4b022f1e12daa02-scarletchains-1338391770089-geo1.bmp

Answer 1

hmm not sure why you can't just use the alternate interior angle theorem again

Answer 2

idk:/ i dont understand this stuff!:/

Answer 3

and these are the only choices possible?

Answer 4

yes!

Answer 5

alright, one sec

Answer 6

ok thanks:)

Answer 7

the only thing that comes close is Triangle Exterior Angle Theorem, but even that isn't the true answer...so there has to be something missing


but if I were to guess, that'd be my answer

Answer 8

the true answer should be "alternate interior angles", but sadly that's not an answer choice

Answer 9

let me know how it works out

Answer 10

ok i will.... thank you so much hun ur a lifesaver! :)

Answer 11

you're welcome

Answer 12

it was wrong:/

Answer 13

dang...did it say which one it was?

Answer 14

no it didnt:( grrr its ok thanks for tryin!

Answer 15

yeah tell me about it, it's very frustrating when the correct answer isn't even on the list and they won't even tell you the correct answer.