In Figure 4.6, P1 and P2 are (perfect) dipoles a distance r apart. What is the torque

Question:

In Figure 4.6, P1 and P2 are (perfect) dipoles a distance r apart. What is the torque on P1 due to p2? What is the torque on P2 due to P1? [In each case I want the torque on the dipole about its own center. If it bothers you that the answers are not equal and opposite, see Prob.4.29.]