\text { Evaluate } \iint_{R} \arctan \left(\frac{y}{x}\right) \mathrm{d} \mathrm{A} \text { where } R=\left\{(x, y) \mid 1 \leq x^{2}+y^{2} \leq 4,0 \leq y \leq x\right\} by changing the to polar

coordinates. Step 1: Specify the range of D=:{ (r, e )| <=r<= , <=0<= } Step 2: Evaluate the integral.