Answer
$2y^2-x=1$
Work Step by Step
We know that $\cos^2 A+\sin^2 A=1$. $\cos t=y,\cos 2t=\cos^2 t-\sin^2 t=x$
Hence here $2y^2-x=1$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.