I need help with proving that the measures of the interior angles of a triangle is 180 degrees.

Question

amistre64 · Answer

draw a parallel line thru one of the vertexes, that is parallel to the other side ...

amistre64 · Answer

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anonymous · Answer

I have gotten that far.

amistre64 · Answer

what are angles called so that we can equate them like i did?

amistre64 · Answer

and what is the measure in degrees of a straight line?

anonymous · Answer

alternate interior?

anonymous · Answer

180 degrees for a straight line.

amistre64 · Answer

alt interior yes; that allows us to move a and c to the top

amistre64 · Answer

now a+b+c = 180 by some straight line property

anonymous · Answer

What do you mean by straight line property?

amistre64 · Answer

i mean, that i can never remember what they call these things .... the names should be better suited to you since you are fresh in the course.

amistre64 · Answer

straight angle definition maybe?

amistre64 · Answer

since a,b,c add create a straight line, then they add up to 18o degrees,

anonymous · Answer

but is that enough for this proof?

amistre64 · Answer

should be

what was it we were trying to prove?

anonymous · Answer

That the sum of the interior angles of a triangle are 180 degrees.

amistre64 · Answer

we show that the three angles of a triangle form a straight line ... and thereby have a sum of 180

amistre64 · Answer

thats proof enough for me

anonymous · Answer

Thanks.

amistre64 · Answer

good luck

anonymous · Answer

I need more help with this