COMEDK · Maths · 4. Permutation Combination
Out of 10 given point, 3 are collinear. How many different straight line can be drawn by joining any 2 points from those 10 points?
- A 40
- B 36
- C 42
- D 43
Answer & Solution
Correct Answer
(D) 43
Step-by-step Solution
Detailed explanation
If there are \(m\) points in which \(n\) points are collinear \((m \geq n)\) then number of different straight line are \({ }^m C_2-{ }^n C_2+1\) \(\Rightarrow{ }^{10} C_2-{ }^3 C_2+1=\frac{10 \times 9}{2}-3+1=45-3+1=43\)
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