Rectangular and parametric forms of conic sections?

Find the rectangular equation of the curve whose parametric equations are given.

1.x=-cost t, y= sin t

2. x=-sin 2t
y=2 cos 2t

Now I am kind of confused what to for with the the "2t"

For example on number 2 I did

2 cos 2t=y
cos2t=y/2 Would I do know square it but while I would get y^2/4 on one side what would I do on the "other side"?(Giggle)

Quote:

---

Originally Posted by homeylova223

Find the rectangular equation of the curve whose parametric equations are given.

1.x=-cost t, y= sin t

2. x=-sin 2t
y=2 cos 2t

Now I am kind of confused what to for with the the "2t"

For example on number 2 I did

2 cos 2t=y
cos2t=y/2 Would I do know square it but while I would get y^2/4 on one side what would I do on the "other side"?(Giggle)

---

You have a good start but you need to keep going and use the Pythagorean identity.

So would the answer to my first question be

(-x)^2+ (y)^2=1
x^2+y^2=1

Yes