# Thread: parametric equations of a curve

1. ## parametric equations of a curve

A curve: x=(1+t)^0.5, y=(1-t)^-0.5

After plotting the curve I don't see any turning points. I can see a vertical asymptote at x=2^0.5.

I have calculated that there is a stationary point at t=-1 and the point (0,2^-0.5). I don't see it on the graph though. At that point the second derivative is 0.25*(2^0.5) and hence greater than 0 and there is a minimum turning point.

The answers give the point (0,2^0.5) and says it is a minimum end point.

2. ## Re: parametric equations of a curve

Originally Posted by Stuck Man
I don't see it on the graph though.
The point, or it looking like a starionary point? It's there.

Originally Posted by Stuck Man
The answers give the point (0,2^0.5)
Must be a typo.

Originally Posted by Stuck Man
and says it is a minimum end point.
i.e. would be a minimum turning point if it wasn't an end point.

3. ## Re: parametric equations of a curve

Left of the supposed stationary point the graph slope down slightly as if there is a horizontal asymptote. The point is not an end point.

5. ## Re: parametric equations of a curve

Originally Posted by Stuck Man
A curve: x=(1+t)^0.5, y=(1-t)^-0.5

After plotting the curve I don't see any turning points. I can see a vertical asymptote at x=2^0.5.

I have calculated that there is a stationary point at t=-1 and the point (0,2^-0.5). I don't see it on the graph though. At that point the second derivative is 0.25*(2^0.5) and hence greater than 0 and there is a minimum turning point.

The answers give the point (0,2^0.5) and says it is a minimum end point.
1. You certainely have determined that $-1 \leq t < 1 ~\implies~ \left\lbrace \begin{array}{rcl}0\leq x \leq \sqrt{2} \\ y \ge \frac1{\sqrt{2}}\end{array}\right.$

2. Your curve is the right branch (drawn in red) of the graph of $\displaystyle{f(x)=\frac1{\sqrt{2-x^2}}}$ (drawn in green)

3. Obviously the left end point is a minimum with a horizontal tangent.

6. ## Re: parametric equations of a curve

You can see that $\left( {0,\frac{1}{{\sqrt 2 }}} \right)$ is a minimum.

7. ## Re: parametric equations of a curve

My graphing program is displaying an incorrect line on the left of x=0. It is GraphCalc from 2003. Is there any others you know about?