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# Parametric Equation watch

1. Attachment 731010731012
19 ii) We haven't been given any value for t, so I found t = 0, by setting sin2t = 0, since when x intercepts the axis y is 0. But this only gave me one of the the points on the graph.
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2. (Original post by znx)
19 ii) We haven't been given any value for t, so I found t = 0, by setting sin2t = 0, since when x intercepts the axis y is 0. But this only gave me one of the the points on the graph.
Well there are multiple solutions to the equation in the region . You find them all the time in C2 and C3.
3. (Original post by RDKGames)
Well there are multiple solutions to the equation in the region . You find them all the time in C2 and C3.
thank you, forgot about the rest of the solutions
4. (Original post by RDKGames)
Well there are multiple solutions to the equation in the region . You find them all the time in C2 and C3.
For part iii) I've got it in the form Rcos(t-a), where R is √5 and a is 1.1
For the coordinates of C, I got it as (1.1, √5) however the answer is (√5, 4/5) and im not sure why?
5. (Original post by znx)
For part iii) I've got it in the form Rcos(t-a), where R is √5 and a is 1.1
For the coordinates of C, I got it as (1.1, √5) however the answer is (√5, 4/5) and im not sure why?
You found the max on the t-x graph, and not on the x-y graph.
6. (Original post by RDKGames)
You found the max on the t-x graph, and not on the x-y graph.
So the x should be √5, but why is y's coordinate found by sin(2a)? and not tan(a) or sin(a)?
7. (Original post by znx)
So the x should be √5, but why is y's coordinate found by sin(2a)? and not tan(a) or sin(a)?
Because the max x coordinate occurs when . Clearly the y coordinate for this is .
8. (Original post by RDKGames)
Because the max x coordinate occurs when . Clearly the y coordinate for this is .
Thank you

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