16. If 10 parallel lines in a plane is intersected by a family of another 8 parallel lines, how many parallelograms are there in the network thus formed?
a) 80
b) 63
c) 120
d) 1260

• parallelogram can formed by 2 horizontal and 2 vertical lines
  for horizontal 10c2
  for vertical 8c2
  total parallelogram is 10 c2*8c2=45*28
  =1260
• 8 years agoHelpfull: Yes(20) No(1)
• 1260
  10c2* 8c2
• 8 years agoHelpfull: Yes(19) No(1)
• 10C2*8C2 = 1260 formed
• 8 years agoHelpfull: Yes(1) No(0)
• If m parallel lines in a plane are intersected by a family of n parallel lines.The no. of parellelograms formed will be mn(m-1)(n-1)/4
  given m=8 and n=10
  Hence no.of parallellograms formed=(80*7*9)/4=1260
• 7 years agoHelpfull: Yes(1) No(0)
• d
  because from ten 10c2*8c2
• 8 years agoHelpfull: Yes(0) No(0)
• parallelogram have two horizontal& two vertical lines then our solution is 10 c 2 *8 c 2=1260.
• 8 years agoHelpfull: Yes(0) No(0)
• 1260
  selecting two lines from one set of 10 paralle lines and selecting other 2 line from one set of 8 parallel lines
  10c2*8c2=1260
• 8 years agoHelpfull: Yes(0) No(0)
• 10c2*8c2 =1260
• 7 years agoHelpfull: Yes(0) No(0)