-54 i think is the answer
Answer:
SSS
Step-by-step explanation:
I can identify that these triangles are congruent by using the SSS (Side, Side, Side) postulate theorem. I know this because first, second, and home triangle share the same side as the third, second, and home triangle, meaning they are congruent, so are the other sides of the angle since the question states they are congruent.
Angles ECD and CEF add to 180
40+140 = 180
So that means we have EF parallel to CD (due to the same side interior angle theorem)
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Angles BCE and ECD combine to 30+40 = 70, which is congruent to angle ABC = 70 as well.
In other words, this shows angle ABC = angle BCD. Both of these angles are alternate interior angles. Since they're congruent, they lead to AB being parallel to CD.
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So far we have
AB || CD
CD || EF
Using the transitive property, we can then link the two statements to say AB || EF. Think of a chain where CD is the common link. We go from AB to CD, then from CD to EF. So we can just take a single path from AB to EF.
It's like saying "P --> Q and Q --> R, therefore P --> R"
I believe the answer is
.5
