A boat sailing due east parallel to the shoreline at a speed of 10 miles per hour. At a given time the bearing to the light house is S70 degrees E, and 30 minutes later the bearing is S63 degrees E. Find the distance from the boat to the shoreline if the lighthouse is at the shoreline.

Answer 1

the boat has traveled 5 miles. So, if the distance to shore is d,

d tan70° - d tan63° = 5