COMEDK · Maths · 4. Permutation Combination
There are 10 points in a plane out of which 4 points are collinear. How many straight lines can be drawn by joining any two of them?
- A 39
- B 40
- C 45
- D 21
Answer & Solution
Correct Answer
(B) 40
Step-by-step Solution
Detailed explanation
From 10 given points, \({ }^{10} C_2\) straight lines can be drawn. But 4 points are collinear, using 4 points, \({ }^4 C_2\) straight lines can be drawn. From 4 collinear points, 1 straight line can be drawn. So, total number of straight lines \(={ }^{10} C_2-{ }^4 C_2+1\)…
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