Consider the constant-density solid {(rho,φ,θ):0 π
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,0≤θ≤2π} bounded by two hemispheres and the xy-plane. a. Find and graph the z-coordinate of the center of mass of the plate as a function of a. b. For what value of a is the center of mass on the edge of the solid? a. The z-coordinate of the center of mass is