You are enroute to assist vessel A. Vessel A is underway at 6 knots on course 133°T, and bears 042° at 105 miles from you. What is the course to steer at 10 knots to intercept vessel A?

Correct Answer: Option D — 079°

Vector addition using relative motion triangles determines the true course to steer for interception. Plotting your own vessel speed of 10 knots against Vessel A's vector (6 knots on 133°T) originating from 042° at 105 miles results in an intercept course of 079°T.