Chapter 13.2, Problem 56E

Finding a Limit Using Polar Coordinates In Exercises 51-56, use polar coordinates to find the limit. [Hint: Let $x=r\cos \theta$

and $y=r\sin \theta$, and note that $(x,y)\to (0,0)$

implies $r\to 0$

.]

$\underset{(x,y)\to (0,0)}{\lim }\sin \sqrt{x^2+y^2}$