How many straight lines can be formed?
Explanation:
If we select any two non-collinear points we will get a different line except when we select the 5 collinear points, we will get the same line again and again.
Total number of ways of choosing 2 points = 15C2 = 105.
For collinear set of points, number of selecting 2 points = 5C2 = 10.
Now each of these 10 lines is same hence, we will subtract these 10 lines and add 1 line.
∴ Required answer = 105 – 10 + 1 = 96.
Hence, 96.
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