.working in (Real)^2

{(x, 0) : sin x ≥ 0}

I Know this set is closed but is unbouned. But i am finding it different to show this.

Did you mean "difficult" instead of "different"? Let .

Now, let (why??) , and

thus the complement of is an open set (why?)

{(x^3y - z^2; xyz + y^3z) : 0 =< x, y,z =< 1).}

Try to do something similar to the above

Tonio

I finding it difficult to show this is closed.

Thanks for helping