Chapter 10 - Parametric And Polar Curves; Conic Sections - 10.1 Parametric Equations; Tangent Lines And Arc Length For Parametric Curves - Exercises Set 10.1 - Page 701: 13

$$x=5 \cos t; y=-5 \sin t; 0 \leq t \leq 2\pi$$

When $t=0$ , then the circle is traced clockwise by a point that originates at $(5,0)$ and it completes one full circle of revolution when $t=2 \pi$ . So, parametric equations for the curve $x^2+y^2=5$ are: $$x=5 \cos t; y=-5 \sin t; 0 \leq t \leq 2\pi$$