1. Walking-competition: Calculate the angle , use Cosine rule to calculate the distance AC.
2. Tanker: Calculate the sides of the triangle P1100, P1200, LH using Sine rule. Afterwards calculate the length of the height from LH to the base P1100P1200.
The distance fromm P1100 to the foot point of the height indicates the time from 11:00 o'clock when the lighthouse is nearest to the tanker (11:24 o'clock)