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# C4 Parametric Equations- Help Appreciated watch

1. A curve is given by the parametric equations x=sint, y=tant.

For : - pi/2 < t < pi/2

Draw a graph of the curve.

I did:

t = -pi/2

Put it into calc and got x = 1 but for y, I get math error.

2. Well that means you have an asymptote at (incidentally there's also another one), which is why the < signs are there, rather than .

Your best bet is to substitute in and look at the behaviour as . When you've got a few points plotted, the shape of the graph should become clear.
3. (Original post by nuodai)
Well that means you have an asymptote at (incidentally there's also another one), which is why the < signs are there, rather than .

Your best bet is to substitute in and look at the behaviour as . When you've got a few points plotted, the shape of the graph should become clear.
The answers have (-1, -4) and (1, 4) through which the curve passes through. I don't know how they get this though?
4. (Original post by Deep456)
The answers have (-1, -4) and (1, 4) through which the curve passes through. I don't know how they get this though?
Bizarre... well it doesn't
5. (Original post by nuodai)
Bizarre... well it doesn't
Thanks. Back to C4.
6. Alternatively note that:
for .

Also note that this condition on t implies that , .

Therefore .

Which clearly passes through the origin and has asymptotes at .

Additionally , so by considering the value of this as t varies, we can find out how the gradient behaves over the required interval.

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Updated: December 23, 2010
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