Question

Which set of rectangular coordinates describes the same location as the polar coordinates (-2,2pi)

Answer 1

`\bf (\stackrel{\stackrel{r}{\downarrow }}{-2}~~,~~\stackrel{\stackrel{\theta }{\downarrow }}{2\pi })\qquad \begin{cases} x=&rcos(\theta )\\ &(-2)cos(2\pi )\\ &(-2)(1)\\ &-2 \\\cline{1-2} y=&rsin(\theta )\\ &(-2)sin(2\pi )\\ &(-2)(0)\\ &0 \end{cases}\qquad \implies \qquad (\stackrel{x}{-2}~,~\stackrel{y}{0})`

Answer 2

y = rsen (θ)

So for r = -2 and θ = 2π we have

x = -2cos (2π)

x = -2

y = -2sen (2π)

y = 0

Finally the equivalent point in Cartesian coordinates is the point:

(-2 0)

Explanation: