1.

If 7 points out of 12 are in the same straight line, then the number of triangles formed isA. 84B. 175C. 185D. 201

Answer» Correct Answer - C
Number of triangle formed from 12 point `= .^(12)C_(3)`
Since 7 parts are collinear, then `.^(7)C_(3)` triangles will not be formed so. ltbr. `= .^(12)C_(3) - .^(7)C_(3)`
`= (12!)/(3!9!) - (7!)/(3!4!) = (12.11.10)/(3.2.1) - (7.6.5)/(3.2.1)`
`= 220 - 35 = 185`


Discussion

No Comment Found

Related InterviewSolutions