Maths alevel - parametric

Hi,
I am stuck on working on the domain. I have already worked out the cartesian equation.
x= sec^2t+1 y=2sint -pi/4<t<pi/4
cartesian equation: y=square root of (8-4x/1-x)

How would I work out the domain and range?
The answer for the domain is x <1 or x>2

Thank you,
P.Abira

Domain: sub t into the expression for x and see what range it gives,then check that to make sure you can calculate the sqrt() expression in the cartesian equation.
Range: sub the values from the domain into the cartesian equation

May help:
https://www.desmos.com/calculator/oximuosldk

I did sub in the value of t :-pi/4 in to the x expression, but instead i got x=3 for both positive and negative t values (pi/4).

However, the answer says x <1 or x>2.

Also what do you mean by this: '' then check that to make sure you can calculate the sqrt() expression in the cartesian equation.''

Thanks