3-21. Consider a two-link planar robot, with positive orientations of 1 and 2 as shown in Fig. P3.18. (b) Suppose now that the same robot is
located in the fourth quadrant and
is oriented in the “elbow-up” position (i.e., with a positive value of 2).
If the tip of the robot is located
point at P(x, y)=(6,−4), determine
the values of 1 and 2 .