InterviewSolution
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InterviewSolution
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The number of triangles that can be formed by choosing the vefrom a set of 12 points, seven of which lie on the same straight line, are:A. 185B. 175C. 115D. 105 |
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Answer» Correct Answer - A To form a triangle, we need 3 points. 12 points are given. So, `.^(12)C_(3)` triangle can be formed ltbr. But, givne that 7 points are on a straight line. Selecting 3 points from this set will not form a triangle So, number of triangle formed `.^(12)C_(3) - .^(7)C_(3)` `= (12!)/(3!9!) - (7!)/(3!4!)` `= (12 xx 11 xx 10 )/(3 xx 2 xx 1) - (7 xx 6 xx 5)/(3 xx 2 xx 1) = 220 - 35 = 185` |
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