Final answer:
Knee joints function like a hin_ge and are formed by the tibia and femur, allowing bending and straightening of the leg. The hip joint, however, is a ball-and-socket joint that provides a wider range of motion than the knee.
Step-by-step explanation:
Knee joints and hip joints are both crucial for movement but have different structures and functions. The knee joint works like a hin_ge, allowing the leg to bend and straighten, and is formed by the tibia (lower leg bone) and the femur (thighbone). Conversely, the hip joint is a ball-and-socket joint, where the ball at the end of the femur fits into the socket part of the pelvis, enabling a broader range of motion in multiple directions. Both joints are covered in cartilage and produce synovial fluid to reduce friction, essential for dancers when creating their steps.