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An ornithologist is in the field studying a formation of geese and is 180 m south, and...

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user354582 | Honors

Posted July 11, 2013 at 6:13 AM via web

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An ornithologist is in the field studying a formation of geese and is 180 m south, and 385 m west, of where she parked her car.

Let u be the vector representing the distance between the ornithologist and her car, and let v be the vector representing the straight line distance from the ornithologist to the formation.

If the lead goose flies over her car at an altitude 319 m

find |v|

find the angle btw u and v using cos `theta` = u.v/|u||v|

Verify result using right angle trig.

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted July 11, 2013 at 6:46 AM (Answer #1)

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An ornithologist is in the field studying the formation of geese. She is  180 m south, and 385 m west of where she parked her car. The lead goose flies over her car at an altitude of 319 m. `vec u ` represents the vector from the ornithologist to her car. `vec v ` represents the vector from the ornithologist to the lead goose.

Let the point where the ornithologist is standing be (0,0,0). The vector `vec u` is [180, 385, 0] and the vector `vec v` is [180, 385, 319]

The magnitude of `vec v` is `sqrt(180^2 + 385^2 + 319^2)` = 531.4

The magnitude of `vec u` is `sqrt(180^2 + 385^2)` = 425.

The angle `theta` between `vec u` and `vec v` is defined as `cos theta = (180^2 + 385^2 + 0)/(531.4*425)`

=> `theta = cos^-1(2125/2657)` = 36.89 degrees

Using the right triangle formed the angle is `tan^-1(319/425)` = 36.89 degrees

The angle between the vectors is verified to be 36.89 degree.

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