A student writes an incorrect step while checking if the sum of the measures of the two remote interior angles of triangle ABC below is equal to the measure of the exterior angle.

Question

anonymous · Answer

attachment

anonymous · Answer

attachment

anonymous · Answer

@jim_thompson5910

jim_thompson5910 · Answer

how far did you get? are you able to eliminate any false statements?

anonymous · Answer

I'm completely lost, but i dont think it's B

jim_thompson5910 · Answer

|dw:1425523967967:dw|

jim_thompson5910 · Answer

based on that, do you agree with step 1?

anonymous · Answer

no

jim_thompson5910 · Answer

why not?

anonymous · Answer

it just doesn't look like it fits

jim_thompson5910 · Answer

it turns out that $\large m\angle x+m\angle y+m\angle z = 180^{\circ}$ is actually true

jim_thompson5910 · Answer

for ANY triangle, adding up the 3 angles ALWAYS gives you 180 degrees

anonymous · Answer

So which one isn't true?
I'm sorry, im in a huge hurry. Can you telly me the answer, but WHY it's the answer? I would like to still learn but i'm in a massive rush

anonymous · Answer

nvm, the answer was the second one

anonymous · Answer

Wait so what was the answer?