how many diagonals are there in
a) a quadrilateral?
b) a pentagon?
c) a hexagon
2007-07-29 18:47:53 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
a quaderalateral os n sides has nC2 -n= n(n-1)/2x1 -n
(n^2 - 3n)/2
a) a quad. then n=4 ,then number of diagonals 16-12/2 = 2
b)pentagon then n=5 ,then number of diagonals 25-15/2 = 5
c) hexagon then n=6,then number of diagonals 36-18/2 =9
2007-07-29 19:26:01 · answer #1 · answered by mramahmedmram 3 · 0⤊ 0⤋
d = n(n-3)/2 So for :
quadrilateral = 4(4-3)/2 = 2
pentagon = 5(5-3)/2 = 5
hexagon = 6(6-3)/2 = 9
2007-07-30 02:00:24 · answer #2 · answered by ironduke8159 7 · 1⤊ 0⤋
Quadrilateral has 2 diagonals
Pentagon has 5 diagonals
Hexagon has 9 diagonals
Hope that is what you want.
2007-07-30 01:55:58 · answer #3 · answered by Moe 2 · 0⤊ 1⤋