Eliminate the parameter.

x = 3 cos t, y = 3 sin t
I got to the part where its (x/3) = cos t. where do I go from now?

Question

Eliminate the parameter.

x = 3 cos t, y = 3 sin t 
I got to the part where its (x/3) = cos t. where do I go from now?

anonymous · Answer

Now, you want to use: $$
\cos^2(t)+\sin^2(t) = 1
$$

anonymous · Answer

would I use that in place of cos to cancel out the right side and leave t, and the right side would be cos^2(x/3) = t?

anonymous · Answer

$$
x^2+y^2=(3\cos t)^2+(3\sin t)^2
$$

anonymous · Answer

im still confused. :( I just don't get how to eliminate the parameters in the questions with trig functions

anonymous · Answer

Simplify

anonymous · Answer

$$
=9(\cos^2t+\sin^2t)
$$The $t$ will go away

anonymous · Answer

how would the t go away? could you show me the whole process please with an explanation?:)

anonymous · Answer

Do you know algebra?

ganeshie8 · Answer

```
x = 3 cos t, y = 3 sin t 
I got to the part where its (x/3) = cos t. where do I go from now?
```


how did you get (x/3) = cos t ?

anonymous · Answer

OH so would the answer be (x^2/9) + (y^2/9) = 1???

ganeshie8 · Answer

yes thats right!
but nobody leaves the equation of circle in that form. you may want to kick that 9 to the right side

ganeshie8 · Answer

multiply 9 through out

anonymous · Answer

ok thank you so much!!!! you guys all rock:)

anonymous · Answer

is it possible to give both of you guys medals??

ganeshie8 · Answer

Notice, you need to know few trig identities to work these... time to revise your trig

ganeshie8 · Answer

$$\sin^2t + \cos^2t=1$$
you would be using this identity a lot, definitely worth memorizing