perimeter is sum of all sides
in case it is
1 + 4 + 4 + 0.5 + 0.5 + 2.5 + 2.5
=> 1 + 8 + 1 + 5
=> 10 + 5 = 15cm
four types of cells compose bony tissue: osteocytes, osteoclasts, osteoprogenitor cells, and osteoblasts. ossification is the process of bone formation by osteoblasts. long bones lengthen as chondrocytes divide and secrete hyaline cartilage. osteoblasts replace cartilage with bone.