1. ## Change of variables

Evaluate by switching to polar coordinates:
$\iint_D \sqrt{x^2+y^2} dA$. where D is the semicircle of radius 1 centered at (1,0) and $y\geq 0$

Having difficulties determining r

2. Originally Posted by Pur
Evaluate by switching to polar coordinates:
$\iint_D \sqrt{x^2+y^2} dA$. where D is the semicircle of radius 1 centered at (1,0) and $y\geq 0$

Having difficulties determining r
$(x - 1)^2 + y^2 = 1 \Rightarrow x^2 - 2x + 1 + y^2 = 1 \Rightarrow r^2 - 2 r \cos \theta = 0 \Rightarrow r = 0$ or $r = 2 \cos \theta$.