Just list them. Points A, B, C, D, E
AB, AC, AD, AE - 4
BC, BD, BE - 7
CD, CE - 9
DE - 10
I'm not sure what it was you were trying to draw.
ok so here is the question...
ok so there are 5 points on a circle, and if two points form a segment, how many segments are there. what is the number of line segments.
this seemed straight forward, i chose my answer to be 7. i made a circle and connected the points careful not to double back, my book says the answer is 10? where did i go wrong?
and you know what there is a pattern. ok the problem said there were 5 points. ok so if i subtract 1 from 5 and then add 4+3+2+1 i get the answer? i thought it was a fluke, but then i tried it on another problem and it worked? can you tell me why this is true? whats actually going on here?
OK, without any advanced math technics:
If you have n points than you can draw (n - 1) segments connecting each point with every other point. That means you have
segments.
Since you have drawn every segment twice you have to divide by 2 to get the correct result:
(n := number of points; s := number of segments)