kablayi wrote:
walker wrote:
C
1. we cannot create triangles for 5 points of a line but can do that for points that are not collinear. insuff.
2. we don't know the number of points insuff.
1&2 \(C^5_3=\frac{5*4*3*2}{3*2*2}=10\)
Can you please write formula to calculate the number of triangles if only 3 points are coliner
Hello
Ok, here's a general formula for calculating possible number of triangles.
If there are N points in a plane, and no three of them are collinear, then the number of possible triangles = N(C)3. (
number of possible selections of 3 objects from N objects)
If there are N points in a plane, and X of them are collinear, then the number of possible triangles = N(C)3 - X(C)3. (
subtracting number of possible selections of 3 objects from X FROM number of possible seelctions of 3 objects from N).
Now to answer your question: IF we were given that there are 5 points in a plane, out of which 3 are collinear, then number of possible triangles would have been = 5C3 - 3C3 = 10 - 1 = 9. Thus 9 triangles would have been possible.