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# C4 Question! watch

1. Hi,

I'm a bit stuck on this question, where you are told that a curve has parametric equations

x=2cot t, y=2sin²t, 0<t<pi/2

You're told to find the cartesian equation of the curve in the form of y=f(x) which I did correctly and got y=8/(4+x²). But then it says to 'State the domain on which the curve is defined' and I don't know how to get this. The domain is x=>0, but how do I obtain this?

Thanks!
2. You are given the parametric domain as: 0<t<pi/2
and x=2cot t

The domain of f(x) is the range of possible x-values.

Substitute in for the range of t-values to get this range.
3. (Original post by sweet_gurl)
Hi,

I'm a bit stuck on this question, where you are told that a curve has parametric equations

x=2cot t, y=2sin²t, 0<t<pi/2

You're told to find the cartesian equation of the curve in the form of y=f(x) which I did correctly and got y=8/(4+x²). But then it says to 'State the domain on which the curve is defined' and I don't know how to get this. The domain is x=>0, but how do I obtain this?

Thanks!
The domain is the values of x for which the curve can be drawn.

If x = 2cott on 0<t<pi/2 you get that x=2/tant, and since tant takes values on 0<=tant<infinity you get that x>=0 only. Thus the domain for your function is x>=0

Hope that helps!

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