Identifying Parametric Equations from Graphs

[Slimsta]

Homework Statement

http://img704.imageshack.us/img704/5760/pqg.jpg

Homework Equations

The Attempt at a Solution

So i know that graph 2 is C
also i know that A and G can't be any of those because its a circular shape..

the rest i have no idea how to do in order to get those crazy graphs

 

[HallsofIvy]

1 and 3 are clearly not periodic- x and y both have an overall increase. That tells you that they are not simply trig functions and that excludes A, B, C, and G. They do appear to have a symmetry about the line y+ x= some number. D is not symmetric so that's excluded leaving only E and F which, because of the "t" added increase steadily as t increases. Subtracting off that "t" is the same as rotating the x= y= t line to the x-axis:
E then becomes x= -2sin(t) and y= -2cos(t) while F becomes x= sin(3t) and y= sin(4t). It should be easy to see which of those 1 and 3 correspond to.

 

[Slimsta]

1 and 3 are clearly not periodic- x and y both have an overall increase. That tells you that they are not simply trig functions and that excludes A, B, C, and G. They do appear to have a symmetry about the line y+ x= some number. D is not symmetric so that's excluded leaving only E and F which, because of the "t" added increase steadily as t increases. Subtracting off that "t" is the same as rotating the x= y= t line to the x-axis:
E then becomes x= -2sin(t) and y= -2cos(t) while F becomes x= sin(3t) and y= sin(4t). It should be easy to see which of those 1 and 3 correspond to.

so all you did is just taking the t's out of it??! that makes sense..
one thing i don't really get is how you match it to the graph..
i mean, i could guess because i had 50/50 but my point is to understand it.. because what if i have like 20 graphs to match :/