Question

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

Answer 1

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

Answer 2

I have gotten that far.

Answer 3

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

Answer 4

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

Answer 5

alternate interior?

Answer 6

180 degrees for a straight line.

Answer 7

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

Answer 8

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

Answer 9

What do you mean by straight line property?

Answer 10

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.

Answer 11

straight angle definition maybe?

Answer 12

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

Answer 13

but is that enough for this proof?

Answer 14

should be

what was it we were trying to prove?

Answer 15

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

Answer 16

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

Answer 17

thats proof enough for me

Answer 18

Thanks.

Answer 19

good luck

Answer 20

I need more help with this