parametric curve x=2cost, y=2sint: find perimeter of curve

[Shutterbug424]

Consider the curve given by the parametric equations x=2cost and y= 2sint

I graphed it on my calculator using parametric mode and it gave me what looks like a circle with a radius of 2.

The question then asked to find the perimeter of the curve.

I thought about taking a basic circumference which would yield:

C= 2 pi r = 2 pi (2) = 4 pi

but something tells me that I'm wrong. When I trace the graph on the calculator, the circumference is 2 pi. But does the graph circle around twice, giving me 4 pi?

Any help would be appreciated.

 

[Deleted member 4993]

Re: parametric curve

Consider the curve given by the parametric equations x=2cost and y= 2sint

I graphed it on my calculator using parametric mode and it gave me what looks like a circle with a radius of 2.

The question then asked to find the perimeter of the curve.

I thought about taking a basic circumference which would yield:

C= 2 pi r = 2 pi (2) = 4 pi<<<<<Correct

but something tells me that I'm wrong. When I trace the graph on the calculator, the circumference is 2 pi. But does the graph circle around twice, giving me 4 pi?

Any help would be appreciated.

 

[Shutterbug424]

Re: parametric curve

Thank you!