(Q). How many distinct triangle can be drawn with their with their vertices selected from 10 points, exactly 5 of which are collinear?
Solution:-
10 points could have given us ¹⁰C₃ triangles if no three of them are in a straight line, but as per question 5 of them are in a straight line so we will get ⁵C₃ number of triangle less.
Hence required number of triangle is = ¹⁰C₃ – ⁵C₃
= 120 – 10
= 110 Answer
