# There are 10 points in a plane, out of these 6 are collinear. If N is the number of triangles formed by joining these points, then

## Solution :

If out of n points,  m are collinear, then

Number of triangles = $$^nC_3$$ – $$^mC_3$$

$$\therefore$$  Number of triangles = $$^{10}C_3$$ – $$^6C_3$$

= 120 – 20

= 100

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