Don't the 3 angles of all triangles add up to 180 degrees? My friend said 360.. but I don't know, that doesn't sound right...
2007-10-17 11:23:48 · 16 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
You are right. Your friend must be thinking of quadrilaterals.
All triangles add up to 180 degrees
All quadrilaterals add up to 360 degrees
All pentagons add up to 540 degrees
All hexagons add up to 720 degrees
All n-gons add up to (n-2)*180 degrees
2007-10-17 11:44:24 · answer #1 · answered by Puzzling 7 · 0⤊ 0⤋
I copied this from another website...it explains things pretty well.
From: Doctor Steven
Subject: Re: Geometry, angles in a triangle
Have you ever tried drawing a triangle on a sphere? I think you
will then find the angles add up to more than 180 degrees.
For your problem, though, I think he wants triangles on a flat
surface.
To see why the sum of the degrees of the angles on a triangle add
to 180 look at a rectangle. It has four angles each of 90
degrees. So the sum of its angles is 360 degrees.
Draw the diagonal of this rectangle and you will split the
rectangle into two triangles. Add up all the angles of the
triangles and you should get 360 degrees since the rectangle had
360 degrees (and we didn't expand the rectangle or anything).
Your triangles are exactly alike, so they must have the same
angles in them. Call the upper triangle T1 and the lower triangle
T2. Then:
sum of angles in T1 = sum of angles in T2.
sum of angles in T1 + sum of angles in T2 = 360.
The only possible solution is that sum of angles of T1 = sum of
angles of T2 = 180 degrees.
Note that you can create any right triangle just by changing the
lengths of the sides of the rectangle.
To see this for other types of triangles, try using a rhombus or a
trapezoid.
Hope this helps.
-Doctor Steven, The Math Forum
http://mathforum.org/library/drmath/view/57727.html
2007-10-17 11:29:53 · answer #2 · answered by mimi 3 · 0⤊ 0⤋
180
2007-10-17 11:26:49 · answer #3 · answered by redbeluga 3 · 0⤊ 0⤋
180
2007-10-17 11:26:11 · answer #4 · answered by Kent-B-True 4 · 0⤊ 0⤋
No, the three angles of ALL known triangles add up to a beguillion degrees, cause there are so many triangles out there.
No, seriously, it's 180
2007-10-17 11:28:04 · answer #5 · answered by dylan k 3 · 0⤊ 0⤋
180 it is. 360 is for anything with 4 sides
2007-10-17 11:26:35 · answer #6 · answered by jeff_faster 2 · 0⤊ 0⤋
180 degrees is a triangles, 360 is most other polygons.
2007-10-17 11:26:15 · answer #7 · answered by trick 4 · 0⤊ 0⤋
it's 180 degrees
2007-10-17 11:26:13 · answer #8 · answered by Rico 2 · 0⤊ 0⤋
the equation is.. (where n= the sides there are in a shape)
(n-2)*180= the interior angles.
2007-10-17 11:27:11 · answer #9 · answered by Cassiopeia 3 · 0⤊ 0⤋
360 = a circle
180 = a triangle
2007-10-17 11:32:02 · answer #10 · answered by cadaholic 7 · 0⤊ 1⤋