4. Evaluate the following double integrals. 1 (a) cos(x) dx dy (b) 12.r dA where R is the rectangle defined by the a-axis the y-axis, x = 2, and y = 3. (c) [ Ja 12x2 dA, where Q is the quadrilateral defined by the x-axis, the y-axis, and the lines x+y = 1 and x + y = 2.