Question

BA is parallel to DE. m 13 years ago

Answer 1

m<CBA+m<CDE+m<BCD should be 360 degree. can you continue??

Answer 2

@marsss why 360? it's like...an open space, idk. hahaha

Answer 3

Say this is your figure

Answer 4

Draw this line

Answer 5

The angles marked are supplementary (ie, they add up to 180 degrees)

Answer 6

As for the interior angles of the triangle which you saw formed, they also add up to 180 degrees. So adding those to the interior angles of the above drawing, you get 360.

BUT
the measures of the interior angles of the triangle, plus the measures of those interior angles of the parallel lines so marked above, they are also equal to
m<CBA+m<CDE+m<BCD

Hence

m<CBA+m<CDE+m<BCD = 360 degrees

Answer 7

ok. now i know why it's 360 xD thanks! haha!

Answer 8

No problem :)

Answer 9

so the missing angle is 120 :)

Answer 10

Correct...
And lol, you questioned marss 's claim that the angles add up to 360... this is good :D

Answer 11

yeah..haha! sorry if i'm slow. lol

Answer 12

No, I didn't think that, I was lauding your curiosity...

Answer 13

I actually didn't know about that 360 thing until @marss mentioned it, so I had to see it for myself, too :)

Answer 14

if i helped both of you, i'm very happy :)

Answer 15

haha! thanks to @marsss !

Answer 16

and of course to @terenzreignz xD

Answer 17

welcome :)