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Problem. 3 : Evaluate the given integral by changing to polar coordinates. If 32 y dA, D where D is the top half of the disk with center the origin and radius 2. 3x y dA = D Problem. 4 : Evaluate the given integral by changing to polar coordinates. sin (22 + y ) dA, R where R is the region in the first quadrant between the circles with center the origin and radii 4 and 7. sin(x2 + y?) dA = ? RProblem. 12 : Find the volume of the solid that lies under the surface z = Try and above the triangle with vertices (1, 1), (3, 1) and (1, 3). Volume = Problem. 13 : Find the volume of the solid that is bounded by the cylinder y + 2 = 81 and the planes x = 2y, x = 0, and z = 0 in the first octant. Volume =