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marasofia1616

  • 3 years ago

Find the point on the terminal side of θ =3pie/4 that has a y coordinate of 1. Show your work for full credit.

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  1. tjones89
    • 3 years ago
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    |dw:1350326762097:dw|

  2. tjones89
    • 3 years ago
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    the goal is to find the coordinates of the point at the end of that angle. We are told that y = 1 at that point so we just need to find the x coordinate and we're set

  3. tjones89
    • 3 years ago
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    to do this we use the triangle that is made when you draw a line straight down from the point like I have in the drawing

  4. tjones89
    • 3 years ago
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    we know the length of that side is one because we were told that y = 1

  5. tjones89
    • 3 years ago
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    now if we knew the angle inside that triangle we could use the tangent function to find the length of the adjacent side, which I labelled x.

  6. tjones89
    • 3 years ago
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    any idea how we can find it?

  7. marasofia1616
    • 3 years ago
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    tan 3pi/4=1/x?

  8. tjones89
    • 3 years ago
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    nope, you used the wrong angle, we need to find the angle inside that triangle

  9. tjones89
    • 3 years ago
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    |dw:1350328078591:dw|

  10. tjones89
    • 3 years ago
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    the 3pi / 4 is outside the triangle

  11. marasofia1616
    • 3 years ago
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    If I use the Unit Circle and says that 3pi/4 is 135... and I am looking for that inside angle I get that it is equal to 45.

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  12. tjones89
    • 3 years ago
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    right, so now we can use tangent to find x \[\tan(45) = \frac{ 1 }{ x }\]

  13. tjones89
    • 3 years ago
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    isolate x and you've got it

  14. marasofia1616
    • 3 years ago
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    x=-1?

  15. tjones89
    • 3 years ago
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    yep!

  16. marasofia1616
    • 3 years ago
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    got it... thanks!

  17. lbouskila
    • 2 years ago
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    how is x= -1?

  18. AG1997
    • 2 years ago
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    So the point would be (-1, 1)?

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