How do you determine the intersection between parametric curves (t2+2t,3t2+5t) and (2t2+4t,t2+2t)?

As mentioned in the title, I have the following parametric curves:

Red: (t2+2t,3t2+5t)
Blue: (2t2+4t,t2+2t)
A graph from FooPlot

I have tried to write the curves in function form using the method that PatrickJMT demonstrates, but I encountered two ± symbols in the same equation, and I am unsure how to proceed.

How do I find the exact intersections?

Thanks!

1 Answer
Oct 8, 2016

See below.

Explanation:

Defining

f1(x(t),y(t))={t2+2t,3t2+5t} and
f2(x(t),y(t))={2t2+4t,t2+2t}

We can verify that the set of coincidence points only has one element: The point (0,0) at the instant t=0.

The functions

f1(x,y) and f2(x,y) have crosses in two points:

{0,0} and {1.8636,2.02359}

Those points are the solutions of the nonparametric curves

f1(x,y)=1+x16(52512y)1=0 and
f2(x,y)=12(222x)(1+y1)=0