1answer given in book is 751 but i m getting 741
in a plane there are 5 straight lines which all pass through a given point , 6 others which all pass through another given point and 7 others which all pass through a third given point. supposing no other three intersect at any point and no two are parallel, find the number of triangles formed by the intersection of the straight lines
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UP 0 DOWN 0 0 14
14 Answers
1post ur method coz m gettin very large value will try 2 find out mistake :)
1i always hav time fr stdies related things inte i was busy solving this prob
1let group 'A' contains 5 lines..... group 'B' contains 6 lines and group 'C' contains 7 lines
a triangle can be formed using three lines
now no. of triangles formed using two lines from group A and 1 from group B or C = 5C2x6C1 + 5C2x7C1
now no. of triangles formed using two lines from group B and 1 from
group A or C = 6C2x5C1 + 6C2x7C1
now no. of triangles formed using two lines from group C and 1 from group A or B = 7C2x5C1 + 7C2x6C1
no. of triangles formed from each line from all groups = 6C1x7C1x5C1
1hey m gettin 751
ur method is rite u misght hav done sum cal misatke
1YA I HAVE DONE MISTAKE IN CALCULATION....................... THANKS