Out to Sea Teacher Notes Topic Area: Hyperbolas NCTM Standards: Interpret representations of functions of two variables. Solve problems that arise in mathematics and in other contexts. Recognize and apply mathematics in contexts outside of mathematics. Objective The student will be able to write an equation for a hyperbola, evaluate the hyperbola for a specified location, and use the equation of the hyperbola to solve problems involving navigation. Getting Started Discuss with students the properties of a hyperbola. Use a diagram of a hyperbola to show the foci and vertices. Discuss how hyperbolas are used in locating ships via radio waves. Prior to using this activity: Students should have an understanding of hyperbolas. Students should have an understanding of the Pythagorean Theorem. Ways students can provide evidence of learning: The student will be able to write an equation given the foci and a point on the hyperbola. The student will be able to solve problems involving navigation of ships and apply this to other areas such as location of aircraft. Common calculator or content errors students might make: Students may use the formula for an ellipse instead of a hyperbola. Students may use the wrong form of the hyperbola. Definitions: LORAN Formulas Hyperbola: x y a b = 1 Pythagorean Theorem: a + b = c Distance Formula: d= ( x x ) + ( y ) 1 y1
Out to Sea How To The following will demonstrate how to enter an equation and a formula into the Equation Solver Function of the Casio fx-9750gii and graph the resulting equation. Enter the equation ( x 8) + 5 = 13 and solve for x. Enter the formula a + b = c and find the value of b when a = 6 and c = 15. To enter an equation into the Solver function: 1. Highlight the EQUA icon from the Main Menu and press l. To select Solver, press e. To enter the formula, input the following: Lsjjf-8ks+5 skl.13l. The screen should look like the one to the right.. Press u(solv) to see the solution shown at the right. To use the Solver function with a formula: 1. Highlight the EQUA icon from the Main Menu and press l. To select Solver, press e. To enter the formula input the following: afs+agsl.agsl. Note: To input a variable, press a then the key associated with the letters written in red. The screen should look like the one to the right.. To solve for an unknown variable, enter each of the known values and press l. Use the arrow keys to highlight the unknown value and press u(solv).
Out to Sea Activity To locate the position of aircraft and ships, navigators use the LORAN system, which stands for long-distance radio navigation for aircraft and ships. The system uses synchronized pulses that are sent from transmitting stations which are located at the foci of a hyperbola. These pulses travel at the speed of light (186,000 miles per second) and represent the difference in the times of arrival of an aircraft or ship which is constant on a hyperbola. In this activity, you will be given the location of two stations on shore, 00 miles apart and positioned on a graph at (-100, 0) and (100, 0). A ship is traveling on a path with coordinates (x, 60). The time difference between the pulses from the two transmitting stations is 1000 microseconds (0.001 seconds) and light travels at 186,000 miles per second. Using this information, you will find the x-coordinate for the position of the ship and you will determine where the ship will dock on shore. Questions 1. Use the information above to determine the difference in the distance the pulses travel.. Using the distance formula, find the x-coordinate for the position of the ship. 3. Find the values of c, a, and b for this hyperbola. c = ; a = ; b = 4. Find the equation for the hyperbola that represents these two transmitting stations. 5. What will the x-coordinate be if the ship is 85 miles off shore?
6. How far is the ship from Station at this point? 7. Find the distance from shore for the given x-coordinates. a. x = 150 b. x = 95 Extensions 1. A distress call comes into Station 1 from a ship starting 45 miles off shore. What are the coordinates of the ship?. What is the distance of the ship from Station 1? 3. A rescue helicopter located at Station 1 can travel at 80 mph. A rescue vessel located at Station can travel 75 mph. How long would it take each to reach the disabled ship?
Solutions 1. 186,000 (.001) = 186 miles. d 1 (Station 1 to Ship) = ( x + 100) + 60 d (Station to Ship) = ( x 100) + 60 ( x + 100) + 60 ( x 100) + 60 x = 178 = 186 3. c = 100; a = 186 = 93 c a = b 100 93 = 1351 = b b = 36.8 (0, 0) -a- ------c------ x y 4. = 1 8649 1351 5. x = 34.3 mi. 6. d ( 34.3 100) + 85 = = 158.9 mi.
7. x = 150; y = 46.5 x = 95; y = 9.4 Extension Solutions 1. Coordinates: (-147, 45). Station 1; 65 miles away 3. Helicopter : 48.75 min. Rescue Vessel: 3.3 hrs.