Question

Question asks to use dy/dx to establish the value for t for which the curve achieves an extrema than identify the coordinate points (x,y) of the relative extrema.

Answer 1

the parametric equations are:
x=sint-tcost
y=cost+tsint from t=0 to pi
here is a link to the diagram and the question: http://i45.tinypic.com/29wqolh.png

Answer 2

Sounds like a case where you want to set dy/dx=0.
Note that dy/dx = dy/dt ÷ dx/dt

Answer 3

so i cot t?

Answer 4

cot(t)=0?

Answer 5

That looks right, yes.

Answer 6

Given that the domain is 0 to π, there is only one extremum.
What did you get for (x,y)?

Answer 7

not sure if i did it right but i got 0,pi/2)

Answer 8

sorry (pi/2,0)

Answer 9

I think π/2 is right for y. Check x again. I'll recalculate too just to be sure.

Answer 10

could they both be Pi/2?

Answer 11

No. You got t=π/2, right because that is where cotangent = 0 on that interval, so if you put those in the original equations for x(t) and y(t), it should come out to (1, π/2) for (x,y)

Answer 12

not good with this trig stuff whatsoever lol, i was thinking the cot(t)=0 was going to give the coordinates, dint know you had to plug it back in to the original equations, ty very much

Answer 13

i was stuck on this for quite a while

Answer 14

Right, always reread the question a couple times to make sure you know what to do with the solutions you find.

When in doubt, just remember SOHCAHTOA, Pythagorean Theorem, and unit circle and you'll be fine.

Good luck!