# Answer says to multiply by 2 am I missing something?Watch

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#1
Question - A curve has parametric equations x=t^2-1, y=t-t^3 where t is a parameter.

- Find the area of the finite region enclosed by the loop of the curve?

t=1

The limits are 1 and 0

By integration etc. I get 4/15

But the answer says that the final stage is 4/15 * 2 = 8/15

Am I missing something, I don't get why you have to multiply by to.

Thanks

-N
0
5 years ago
#2
(Original post by REASON_Lighters)
Question - A curve has parametric equations x=t^2-1, y=t-t^3 where t is a parameter.

- Find the area of the finite region enclosed by the loop of the curve?

t=1

The limits are 1 and 0

By integration etc. I get 4/15

But the answer says that the final stage is 4/15 * 2 = 8/15

Am I missing something, I don't get why you have to multiply by to.

Thanks

-N
Did you integrate between t=0 and t=1? If so, you have only got half the area of the loop.
0
#3
(Original post by brianeverit)
Did you integrate between t=0 and t=1? If so, you have only got half the area of the loop.
BALLS! Thats probably it. But how do you know its half the area because I have done other questions where this is not the case and where it is. Because when I worked out the values of t, they were 0 and 1.

However the questions limits where when -2<and equal to t <and equal to 2

Would this have anything to do with it?

Thanks <br>
0
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