There are 25 points in a plane , of which 10 are on the same line.Of the rest,no 3 collinear and no 2 are collinear with any of the 1st 10 points.find the number of different straight lines that can be formed by joining these points

Dear Rahul

Total No. of straight line would be 25C2 but we have to subtract 10C2 because first 10 points will form a line.

So answer is 25C2-10C2+1=256

All the best

AKASH GOYAL
AskiitiansExpert-IITD

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