Hello!!
[tex]\left \{ {{x = 3 cos t} \atop {y = 3 sin t}} \right.
\left \{ {{y^2 = (3 cos t)^2} \atop {x^2= (3 sin t)^2}} \right.
\left \{ {{y^2 = 3^2 cos^2 t} \atop {x^2= 3^2 sin^2 t}} \right.[/tex]
Now add them,
[tex]x^2 + y^2 = 3^2cos^2t + 3^2sin^2t
x^2 + y^2 = 3^2 * (cos^2t + sin^2t) ---> (REMEMBER: cos^2t + sin^2t = 1)
x^2 + y^2 = 3^2 * 1
x^2 + y^2 = 3^2[/tex]
Therefore, the center is at the origin (0,0), and the radius is 3. We eliminated the parameter!
Good luck :)
