3 points = A triangle
Probability
Level
3
Given that there 10 points on a plane, and given that 4 points are aligned in a straight line. If we could connect three points to form a triangle, how many triangles can be made?
The answer is 116.
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1 solution
The total number of triangles that can be formed is 10C3 = 120. But 4 of the points are co linear. So we'll have to subtract the number of triangles which can be formed from these four points which is 4C3 = 4 Thus 120-4 = 116