Parametric Equations help! Watch

TaySwiftie13
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Hi, please could someone help, this is a one mark part of a question from parametric integration. I think im being really silly here but cant work out how they got this answer - its probably so obvious haha

theres a diagramm showing the curve c with parametric equations x=3t^2 and y=sin2t where t is greater than or equal to 0.

write down the value of t at the point a where the curve crosses the x axis (so basically on the diagram theres a curve and a is where it crosses the x axis)

They got t=pi/2 , please help!
thank you!!
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Notnek
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(Original post by TaySwiftie13)
Hi, please could someone help, this is a one mark part of a question from parametric integration. I think im being really silly here but cant work out how they got this answer - its probably so obvious haha

theres a diagramm showing the curve c with parametric equations x=3t^2 and y=sin2t where t is greater than or equal to 0.

write down the value of t at the point a where the curve crosses the x axis (so basically on the diagram theres a curve and a is where it crosses the x axis)

They got t=pi/2 , please help!
thank you!!
A curve crosses the x-axis when y=0 so just set y to 0 and solve the equation. If you’re still stuck please post all your working.
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TaySwiftie13
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hi thanks for you reply, I did that so I got sin2t=0 then I did sin^-1(0) on calculator and that gave me 0!
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Notnek
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(Original post by TaySwiftie13)
hi thanks for you reply, I did that so I got sin2t=0 then I did sin^-1(0) on calculator and that gave me 0!
The graph does the cross the x-axis at t = 0 but I'm assuming your question wants the positive solution? If you're not sure please post the whole question.

I'm sure you're aware that there are infinitely many solutions to \sin x = a and your calculator only gives you one value.
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TaySwiftie13
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yes im aware of that, so how would you know you were looking for the next value?
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Notnek
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(Original post by TaySwiftie13)
yes im aware of that, so how would you know you were looking for the next value?
Can you please post a picture of the question?
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username3435
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post a picture of the question
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