The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

Parametric Equation

IMG_2438.JPG
Attachment not found

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.
IMG_2439.JPG360.6KB
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 sin⁡(2t)=0\sin(2t) = 0 in the region 0≤t≤π0 \leq t \leq \pi. You find them all the time in C2 and C3.
Reply 2
Avatar for znx
znx
OP
10
Original post by RDKGames
Well there are multiple solutions to the equation sin⁡(2t)=0\sin(2t) = 0 in the region 0≤t≤π0 \leq t \leq \pi. You find them all the time in C2 and C3.


thank you, forgot about the rest of the solutions
Reply 3
Avatar for znx
znx
OP
10
Original post by RDKGames
Well there are multiple solutions to the equation sin⁡(2t)=0\sin(2t) = 0 in the region 0≤t≤π0 \leq t \leq \pi. 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?
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.
Reply 5
Avatar for znx
znx
OP
10
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)?
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 t=αt=\alpha. Clearly the y coordinate for this is sin⁡(2t)=sin⁡(2α)\sin(2t) = \sin(2\alpha).
Reply 7
Avatar for znx
znx
OP
10
Original post by RDKGames
Because the max x coordinate occurs when t=αt=\alpha. Clearly the y coordinate for this is sin⁡(2t)=sin⁡(2α)\sin(2t) = \sin(2\alpha).


Thank you :smile:

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you