Two sources of coherent radio waves broadcasting in phase are located as shown below.(Figure 1) Each grid square is 0.5 m square, and the radio sources broadcast at ?=2.0m.
Part A: At Point A is the interference between the two sources constructive or destructive?
Part B: At Point B is the interference between the two sources constructive or destructive?
Part C: At Point C is the interference between the two sources constructive or destructive?
Part D: At Point D is the interference between the two sources constructive or destructive?