A. Your femoral mid-shaft cross-section has a periosteal radius of 12 mm and an endosteal radius of 6mm. Assuming it is a perfectly circular hollow cross section, find the cross-sectional area, cross-sectional moment of inertia, and polar moment of inertia. B. Now assume you fracture your femur at the midshaft and the original bone supports zero stress when the femur is loaded in bending. Assume a perfectly circular callus made of woven bone forms on the periosteal surface. If the bending yield stress of the original healthy cortical bone was 180 MPa, and the outer radius of the woven bone callus is 17 mm, what is the bending yield stress of the woven bone if it supports the same bending moment at yield as the original healthy cortical bone