5.33 () Write down a pair of equations that express the Cartesian coordinates (x1, x2)

for the robot arm shown in Figure 5.18 in terms of the joint angles θ1 and θ2 and the lengths L1 and L2 of the links. Assume the origin of the coordinate system is given by the attachment point of the lower arm. These equations define the ‘forward kinematics’ of the robot arm.