# Need help with conic intersection algebra

1. Feb 22, 2012

### Cacophony

1. The problem statement, all variables and given/known data

Find intersection points of the following.(Conics are centered to origin)

Circle = x^2+y^2=4, Ellipse = (x^2/4)+(y^2/9) = 1

3. The attempt at a solution

So far I have this. (BTW I know the solutions are (-2,0) and (2,0) but I'm still unsure how to get there step by step).

(x^2/4)+(y^2/4) = (x^2/4)+(y^2/9)= 1

What's the next step?

2. Feb 22, 2012

### Dick

If you have (x^2/4)+(y^2/4) = (x^2/4)+(y^2/9) what do you get if you subtract (x^2/4) from each side?

3. Feb 22, 2012

### Cacophony

Oh ok, so the answer is 5y^2=1?

4. Feb 22, 2012

### Dick

Why would you get that? Reread my last post.

5. Feb 23, 2012

### jkristia

I'm not sure exactly how to solve this, but I would look at the vertices of the ellipse and the radius of the circle

6. Feb 23, 2012

### kushan

hey cacophony , just plot the two graphs and you will see the intersection

7. Feb 23, 2012

### Staff: Mentor

But that will probably not help the OP in identifying the intersection points, which is what the problem asks him/her to do.