Q17 of 64 Page 122

If 20 lines are drawn in a plane such that no two of them are parallel and no three are concurrent, in how many points will they intersect each other?

Let first line intersect point =0


2nd line intersect point=1


3rd line intersect point =2+1


4th line intersect point =3+2+1


…………………………………………….


………………………………………….


nth line intersect point =(n-1) +(n-2).....(3)(2)(1) where n=20


=1+2+3....(n−1)



=19×10


=190


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