2006-12-10 00:01:10 · 10 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
there are 5... I'm very sure about this (I am a math teacher)
the formula is d = [s(s - 3)]/2 wherein the s is the side...
pentagon have 5 sides
d = [ 5 ( 5-3 )]/ 2 so there are
d=5 ( 2 )]/ 2
d=[10]/ 2
d=5
you can also apply this to get the diagonals of other polygons
2006-12-10 00:15:13 · answer #1 · answered by racz_jay25 2 · 1⤊ 0⤋
The numbe of diagonals in any polygon is d = n(n-3)/2, where n is the number of sides of the polygon.
The pentagon has 5 sides so number of diagonals =
5(5-3)/2 = (5*2)/2 = 5
A polygon with 100 sides would have 100(100-3)/2 =4850 diagonals
2006-12-10 00:33:39 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋
I shall define diagonal in order to answer this question. A diagonal of a polygon is a line connecting any two non-adjacent vertices. With this definition, a pentagon has five diagonals, for each vertex has two non-adjacent points, so that makes 2 x 5 or 10 diagonals, but I counted each diagonal twice in this, once for each vertex. These diagonals form the five-pointed star present in generals' insignia and in the US Flag.
2006-12-10 00:11:01 · answer #3 · answered by alnitaka 4 · 0⤊ 0⤋
None, because lines between the corners in a pentagon are not called "diagonals"
2006-12-10 00:04:09 · answer #4 · answered by jhstha 4 · 0⤊ 1⤋
Five sides.
Polygon, in geometry, is a closed plane figure formed by the joining of three or more straight lines.
The triangle has three sides; the quadrilateral, has four sides and includes squares, rectangles, and parallelograms; the pentagon has five sides; and the octagon has eight sides. A regular polygon is one that has equal sides and equal interior angles.
2006-12-10 00:05:17 · answer #5 · answered by _PeTaL_D`oR_ 2 · 0⤊ 0⤋
a pentagon has four diagonals
2006-12-10 00:10:57 · answer #6 · answered by James Chan 4 · 0⤊ 0⤋
5C2-5
=5*4/1*2 -5
5 diagonals
2006-12-10 00:46:52 · answer #7 · answered by raj 7 · 0⤊ 0⤋
it has five diagonals.
you can calculate the number of diagonals of any polygon with the following formula numDiagonals = (numSides * (numSides-3))/2
2006-12-10 00:25:25 · answer #8 · answered by Anonymous · 0⤊ 0⤋
The answer is 5 diagonals, i am sure of it....
2006-12-10 00:19:18 · answer #9 · answered by Choco 2 · 0⤊ 0⤋
that would be 5. for a closed figure with even number of sides (hexagon, octagon) we could probably try (n/2)^2
not sure for odd sides...need to think about it...
2006-12-10 00:17:44 · answer #10 · answered by questionvs 2 · 0⤊ 0⤋