Determine the great circle distance and...

Question 1 / 2707066636eea28f7522a1c51b0c8

Question 1 of 2707066636eea28f7522a1c51b0c8

Determine the great circle distance and initial course from LAT 35°17.6'N, LONG 144°23.0'E to LAT 47°36.0'N, LONG 124°22.0'W.

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Question 1 of 27070

Determine the great circle distance and initial course from LAT 35°17.6'N, LONG 144°23.0'E to LAT 47°36.0'N, LONG 124°22.0'W.

🔍 Key Concepts

• Great circle sailing formulas for distance and initial course on a sphere • Converting longitudes East/West to a difference of longitude (DLo) correctly across 180° meridian • Using mid-latitude and general world chart sense to check if the course direction is reasonable

💭 Think About

• First, sketch (mentally or roughly on paper) where both positions lie on the globe and which ocean they are in. From that sketch, should the initial great circle course from the western Pacific toward the NE Pacific be generally northeast, northwest, southeast, or southwest? • Carefully compute the difference of longitude between 144°23.0'E and 124°22.0'W, remembering that East and West longitudes add when they’re on opposite sides of the 180° line. Is your DLo greater or less than 180° and does that make sense for a great circle route? • Use the great circle distance formula with the two given latitudes and your DLo. Is your computed central angle (and resulting distance) closer to 3700, 3900, or 4000 NM?

✅ Before You Answer

• Verify both latitudes are in the same hemisphere (North) and the longitudes are in opposite hemispheres (East and West) before computing DLo. • Check that your initial course points generally from Japan-area waters toward the Pacific Northwest of North America (think: which quadrant relative to true north?). • After calculating, confirm that your resulting distance and initial course pairing is one of the given options and that no other option has both a similar distance and a plausible course direction.

Question 1 of 27070

Determine the great circle distance and initial course from LAT 35°17.6'N, LONG 144°23.0'E to LAT 47°36.0'N, LONG 124°22.0'W.

3931 miles, 048°T

3718 miles, 318°T

3946 miles, 312°T

3881 miles, 042°T

Question 1 / 2707066636eea28f7522a1c51b0c8

Question 1 of 2707066636eea28f7522a1c51b0c8

Determine the great circle distance and initial course from LAT 35°17.6'N, LONG 144°23.0'E to LAT 47°36.0'N, LONG 124°22.0'W.

Back

Question 1 of 27070

Determine the great circle distance and initial course from LAT 35°17.6'N, LONG 144°23.0'E to LAT 47°36.0'N, LONG 124°22.0'W.