
equation
A bird flies linearly, according to the equation
(x,y,z) = (5,6,7) + t[2,3,1]. Assume that the Sun is directly overhead , making the Sun's rays perpendicular to the xyplane which represents the ground. The birds shadow is said to be projected perpendicularly onto the level ground. Find an equation that describes the motion of the shadow.
I got y=3/2x 3/2
I am not sure about my answer.


I did this in a slightly different way (only slightly):
From x= 5+ 2t, t= (x 5)/2.
Then y= 6+ 3t= 6+ 3(x 5)/2= 6+ (3/2)x 15/2= 12/2+ (3/2)x 15/2= (3/2)x 3/2
Saying that the projection is perpendicular means that we can just ignore z.