(This is actually a calculus problem, not a physics one, but physics is based on calculus, so I hope it's fine) 1. The problem statement, all variables and given/known data Eliminate the parameter to find the Cartesian equation of x = (1/2)cos(θ) y = 2sin(θ) 2. Relevant equations x^2 + y^2 = 1 (eq of circle) 3. The attempt at a solution First approach: x^2 + y^2 = (1/4)cos^2(θ) + 4sin^2(θ) = ? I can't get rid of θ because the constant preceding cosine and sine are not equal. 2nd try: y/x = 2sin(θ)/(0.5cos(θ)) = 4 * (sin(θ)/cos(θ)) = y/4x = tan(θ), so θ = arctan(y/4x) But θ is still there. I need an answer in x and y. Thank you for your help.