Please show steps for both questions

11. Let C be the half circle x2 + y? = 4 with a 2 0 then ads = A. 0 B. 2 C. 8 D. 4 E. 1 8. Calculate the mass of the tetrahedron with corners (0, 0, 0), (1, 0, 0), (0, 2, 0), and (0, 0, 4) whose mass density is p(x, y, z) = 2z. 2 - X 4 - 27 - /2/ 4 4 A. 12 B. 2 z dxoi Jz dye 0 D. E. X y 4 - X - Y 2 4 x + 2 4+ 2= 4 4 - 4X - 2Y