he value of lies between - 1 and 1
But when t=2 the value of is which is more than 1 , so it is not possible.

Let P() be the point and Q (0,b,0) be any point on Y axis.
drs of PQ=(
drs of y axis (0,b,0)
Since PQ perpendicular to y axis.hence a1a2+b1b2+c1c2=0

hence the foot of perpendicular will be

To get the odd factors we will get rid of 2's
We will make the selection from only 3's and 5's
Number of ways 3 can be selected from a lot of two 3's= 3 ways ( one 3,two 3's or three 3's)
Number of ways 5 can be selected from a lot of two 5's= 3 ways ( one 5,two 5's or three 5's)
Therefore the number of odd factors is 3600= 3 X 3 =9
then
then, cosine of the angle between these two lines is given by : 
Forming a differential equation representing the given family of curves by eliminating arbitrary constants a and b from yields the differential equation