SOLUTION: Can you help me answer this? Thank you very much :) There is a seven-sided polygon. If there are no three diagonals of this polygon intersected in a common point, then the points

Algebra ->  Points-lines-and-rays -> SOLUTION: Can you help me answer this? Thank you very much :) There is a seven-sided polygon. If there are no three diagonals of this polygon intersected in a common point, then the points      Log On


   



Question 1006379: Can you help me answer this? Thank you very much :)
There is a seven-sided polygon. If there are no three diagonals of this polygon intersected
in a common point, then the points of intersection of these diagonals will divide the diagonals
into how line segments?
a. 80
b. 84
c. 88
d. 90
e. 108

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!

Coming from each vertex, there are 4 diagonals, green%282%29 skipping over one vertex, and red%282%29 skipping over two vertices.
Multiplying 4 diagonals per vertex times 7 vertices, we would count each diagonal twice, so there is a total of 4%2A7%2F2=14 diagonals.
Of those 14 diagonals, 7 skip one vertex and 7 skip two vertices.
The diagonals that skip over one vertex are intersected by the 4 diagonals coming from the skipped vertex,
so they are divided into 4%2B1=5 line segments.
The diagonals that skip over two vertices are intersected by 6 diagonals, 3 coming from each skipped vertex,
so they are divided into 6%2B1=7 line segments.
The total number of line segments in the diagonals is
7%2A5%2B7%2A7=7%2A%285%2B7%29=7%2A12=highlight%2884%29 .