Math Problem Statement

If Jane walks North for 3 miles, turns $45^\circ$ to the right, and then walks another 4 miles, how many miles will Jane be from her starting point? Give your answer as a decimal rounded to the nearest hundredth. (You may use a calculator to compute the approximation.)

Solution

To determine how far Jane is from her starting point, we can treat this as a problem involving the Pythagorean theorem and trigonometry.

  1. Understanding the Problem:

    • Jane starts walking North for 3 miles.
    • Then, she turns 4545^\circ to the right, meaning she walks along a path that forms a 4545^\circ angle with her initial northward path.
    • After turning, she walks 4 miles.
  2. Visualizing the Movement:

    • Jane's walk can be broken down into two parts:
      1. First segment: She walks North for 3 miles.
      2. Second segment: After turning 4545^\circ to the right, she walks 4 miles at a 4545^\circ angle.
  3. Using the Law of Cosines: To find the straight-line distance from her starting point, we can use the law of cosines. The law of cosines is a formula that relates the sides and angles of a triangle:

    c2=a2+b22abcos(C)c^2 = a^2 + b^2 - 2ab \cdot \cos(C) where:

    • a=3a = 3 miles (the first segment),
    • b=4b = 4 miles (the second segment),
    • C=45C = 45^\circ (the angle between the two segments),
    • cc is the distance from the starting point.
  4. Substituting the values: c2=32+422(3)(4)cos(45)c^2 = 3^2 + 4^2 - 2(3)(4) \cdot \cos(45^\circ)

    Since cos(45)=220.7071\cos(45^\circ) = \frac{\sqrt{2}}{2} \approx 0.7071, we substitute that value in:

    c2=9+162(3)(4)0.7071c^2 = 9 + 16 - 2(3)(4) \cdot 0.7071 c2=25240.7071c^2 = 25 - 24 \cdot 0.7071 c2=2516.9704c^2 = 25 - 16.9704 c2=8.0296c^2 = 8.0296 c=8.02962.83c = \sqrt{8.0296} \approx 2.83

Thus, Jane is approximately 2.83 miles from her starting point.


Would you like more details on the solution process, or do you have any other questions?

Here are five related questions:

  1. How can the law of sines be applied to a similar problem?
  2. What happens if Jane turns a different angle, say 3030^\circ?
  3. How can we calculate the displacement when the walking path forms a straight line?
  4. What is the difference between using the law of cosines and the Pythagorean theorem?
  5. How do you calculate the total distance traveled along a curved path?

Tip: When using the law of cosines, remember to check whether the angle between the two sides is given or needs to be calculated!

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Law of Cosines
Pythagorean Theorem

Formulas

c^2 = a^2 + b^2 - 2ab * cos(C)

Theorems

Law of Cosines

Suitable Grade Level

Grades 8-10