I was asked to parameterize the circle edge of $d_2 =\{(x,y):x^2+y^2=9$ and $x+y\ge0\}.$
Anyways I parametrized the circle edge within the bounds but now I have to find the tangent vector at $(0, 3)$ and I am not exactly sure how to do that. Would I set $(-3\cos(t), 3\sin(t))$ equal to its bounds then solve first? Like $-3\cos(t)=\pi/4, 3\sin(t)=5\pi/4$ and then find $r'(t)$?