How many triangles can be drawn by means of 9 non-collinear points
84
72
144
126
The number of triangles are 9C3 = 84
There are 8 non-collinear points. How many triangles can be drawn by joining these points?
There are 20 non-collinear points in a plane. How many (a) straight lines (b) triangles can be drawn by joining these points?