The number of triangles that can be formed by choosing points from 7 points on a line and 5 points on another parallel line is _________.
Explanation:
7 points lie on a line and 5 points on another parallel line.
A triangle can be formed by 2 points on one of these lines and third point on the other line.
Case 1: 2 points are chose on line with 7 points and 3rd point is chosen on line with 5 points. ⇒ Number of such triangles = 7C2 × 5C1 = 21 × 5 = 105
Case 2: 1 point is chose on line with 7 points and 2 points are chosen on line with 5 points. ⇒ Number of such triangles = 7C1 × 5C2 = 7 × 10 = 70
∴ Total number of traingles = 105 + 70 = 175.
Hence, 175.
» Your doubt will be displayed only after approval.
Help us build a Free and Comprehensive Preparation portal for various competitive exams by providing us your valuable feedback about Apti4All and how it can be improved.