Q. The number of parallelograms that can be formed from a set of four parallel lines intersecting another set of three parallel lines, is
A) 6
B) 18
C) 12
D) 9
Explanation
(c)
From the first set, the number of ways of selection two lines $=^{4}C_{2}$
From the second set, the number of ways of selection two lines $=^{3}C_{2}$
Since, these sets are intersect, therefore they from a parallelogram,
$\therefore$ Required number of ways $= \ ^{4}C_{2} \times^{3}C_{2}$
$= 4 \times 3 = 12$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.