Math Problem Statement

A ship leaves a pier on a bearing of S 62° E and travels for 75 NM. It then turns around and continues on a bearing N 28° E for 53 NM. Determine the bearing of the ship from the pier?

Solution

The problem describes the motion of a ship in two segments and asks for the final bearing of the ship from the pier. Let's break it down step by step:

  1. First Leg:

    • The ship travels on a bearing of S62ES 62^\circ E for 75 Nautical Miles (NM).
    • This means the ship moves southeast, forming an angle of 6262^\circ east of due south.
  2. Second Leg:

    • After turning around, the ship moves on a bearing of N28EN 28^\circ E for 53 Nautical Miles.
    • This leg moves the ship northeast, forming an angle of 2828^\circ east of due north.

Steps to solve:

  • Convert bearings to Cartesian coordinates: Bearings can be transformed into directions on an XY-plane where North corresponds to the positive y-axis, and East corresponds to the positive x-axis.

    • First leg: x1=75sin(62),y1=75cos(62)x_1 = 75 \sin(62^\circ), \quad y_1 = -75 \cos(62^\circ)
    • Second leg: x2=53sin(28),y2=53cos(28)x_2 = 53 \sin(28^\circ), \quad y_2 = 53 \cos(28^\circ)
  • Find the total displacement: Add the x and y components from both legs to get the overall displacement vector. xtotal=x1+x2x_{\text{total}} = x_1 + x_2 ytotal=y1+y2y_{\text{total}} = y_1 + y_2

  • Determine the bearing: Using trigonometry, the final bearing of the ship from the pier can be found by calculating the angle of the displacement vector from the north-south axis. θ=tan1(xtotalytotal)\theta = \tan^{-1}\left(\frac{x_{\text{total}}}{y_{\text{total}}}\right) If the displacement is in the first quadrant (both x and y positive), the bearing will be NθEN \theta^\circ E.

Let me calculate the values.The final bearing of the ship from the pier is approximately N82.75EN 82.75^\circ E.

This means the ship is almost directly east of the pier with a slight deviation to the north.

Would you like further details or explanations on any part of this solution? Here are five related questions you might find interesting:

  1. How do you calculate the bearing when given two or more legs of a journey?
  2. Why is the tangent inverse function used to calculate the final bearing?
  3. How would this calculation change if the journey took place on a curved surface (like Earth)?
  4. What is the importance of converting bearings to Cartesian coordinates?
  5. How would the solution change if the ship traveled westward instead?

Tip: Bearings are typically measured clockwise from the north. When calculating bearings from coordinates, always adjust the angle to fit this convention.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Vector Addition
Bearings
Coordinate Geometry

Formulas

x1 = d1 * sin(angle1)
y1 = d1 * cos(angle1)
x2 = d2 * sin(angle2)
y2 = d2 * cos(angle2)
theta = tan^(-1)(x_total / y_total)

Theorems

Pythagorean theorem for vector components
Inverse tangent function

Suitable Grade Level

Grades 9-12