frazzle777
New Member
- Joined
- Oct 14, 2005
- Messages
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- Gender
- Male
- HSC
- 2006
Nine points lie on a plane. Five of these lie on a line l. No other set of three of these points in collinear.
i) How many sets of 3 points can be chosen from the 5 points lying on l.
ii) How many different triangles can be formed using the 9 points as vertices?
Can someone please help me with this?
So far I have completed these steps:
i) 5C3 = 5!/3!2!
= 10
ii) # of Triangles = 9C3 - 5C3 (this is because some triangles cannot be created as the 3 points are ont he same line) Is this process correct?
i) How many sets of 3 points can be chosen from the 5 points lying on l.
ii) How many different triangles can be formed using the 9 points as vertices?
Can someone please help me with this?
So far I have completed these steps:
i) 5C3 = 5!/3!2!
= 10
ii) # of Triangles = 9C3 - 5C3 (this is because some triangles cannot be created as the 3 points are ont he same line) Is this process correct?
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