Precalculus B Lesson 6.2
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Bearing is not well described in the Precalculus textbook. Bearing is defined as "the angle that the line of travel makes with due north, measured clockwise." This is different from direction angle. But we can use bearing to calculate the direction angle.
Example #1
Suppose the bearing of a plane is 350 degrees. Starting from North (the y-axis), we go clockwise for 350 degrees and draw the arrow. This is a bearing of 350 degrees.
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We can convert the bearing to a direction angle. We start from the x-axis and go counter-clockwise until we reach the arrow. We read this as 90 degrees plus the additional 10 degrees. So the direction angle is 100 degrees because 90 + 10 = 100. Therefore a bearing of 350 corresponds to a direction angle of 100 degrees.
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Example #2
Suppose the bearing is 220 degrees. Starting from North, we go clockwise for 220 degrees and draw the arrow.
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To convert he bearing to a direction angle, we start from the x-axis and go counter-clockwise until we reach the arrow. We read this as 180 plus the additional 50 degrees. So the direction angle is 230 degrees.
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