If one of two parallel lines has 7 points on it and the other has 8, how many triangles can be drawn using the points?
a. 168
b. 196
c. 316
d. 364
e. 455
a. 168
b. 196
c. 316
d. 364
e. 455
Line A - 7 Points
Line B - 8 Points
A triangle can be drawn by either taking 2 points in line A & 1 point in Line B or 2 points in Line B & 1 Point in Line B.
2 Points in Line A & 1 Point in Line B
= No of ways of getting 2 points from Line A * No of ways of getting 1 point from Line B
= 7C2 * 8 = 168
2 Points in Line B & 1 Point in Line A
= No of ways of getting 2 points from Line B * No of ways of getting 1 point from Line A
= 8C2 * 7 = 196
Total no of triangles = 168 + 196 = 364.
Ans (D)
