Question

take any five points a b c d and e in such a way that no three points are collinear join them in pairs and answer the following how many lines can be drawn joining two parts at a time explain​

Answer 1

Answer:

We know that joining of any 2 points give a line. Thus the number of lines obtained from 10 points, when no 3 of which are collinear =

10

C

2

=45

Lines obtained from 4 points =

4

C

2

=6

No of lines lost due to 4 collinear points =6−1=5

So required number of lines =45−5=40

Also we know that any triangle can be obtained by joining any 3 points not in the same straight line. Thus number of triangles obtained from 10 different point, no 3 of which are collinear are =

10

C

3

=120

Triangles obtained from 4 points =

4

C

3

=4

Number of triangles lost due to 4 collinear points=4

So required number of triangles =120−4=116

Answer 2

Answer:

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