The quadriceps tendon attaches to the tibia at a 20 angle and 4 cm away from the joint centre at the knee (Figure 1). When a 100 N weight is attached to the ankle 28 cm from the knee joint, how much fore is required of the quadriceps to maintain the leg in a horizontal position? And what is the magnitude and direction of the reaction force at the knee joint? Assume that the shank and the foot weighs 3.9 kg and the centre of mass is located 12 cm from the knee joint 20 100 N 0.04 m 0.28m Figure 1