3thanx...Nishant sir.
Find the no.of triangles that can be formed with the vertices of a polygon of 10 sides as their vertices if
1) the triangle cannot have more than one side in common.
2)the triangle cannot have any side in common with the polygon.
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2 Answers
62First find the number of those triangles which have exactly one side common:
it is equal to chose a side.. and then chose a vertex from the remaining 8 vertices so taht you dont chose the adjecent vertices...
this is equal to 10x(8-2) = 60
also there are some triangles with 2 common sides .. this number equals to 10?
Total no of triangles that can be formed is 10C3 = 240
Removing 10 we get... 230..
For no common side remove 60 more.. you get 170