Parametric equation help :(

Looking at your written working, you just need to square both sides to get the expression for y^2 that the question is asking for. Your earlier attachment is algebraically correct but not in the format asked for in the question. You can always check your algebraic working by plugging something like theta = 1 radian into your calculator.

That is not my working. Ill post my working now

Oh wait i think its right - originally i forgot to factorise at the end so i thought it was wrong

That looks correct to me. Given that the required answer was in terms of y^2, you might have made you life slightly easier by squaring both sides after y = 6cos(theta)sin(theta). That would have avoided the need for square root brackets.

Like this?

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