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katrinaaap

cos theta= - square root 2 divided by 2

  • 11 months ago
  • 11 months ago

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  1. Mertsj
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    \[\cos \theta= -\frac{\sqrt{2}}{2}\]

    • 11 months ago
  2. katrinaaap
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    yeah I need to solve the equation (0<theta<2pi)

    • 11 months ago
  3. Mertsj
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    We see that the cosine is negative. In what quadrants is the cosine negative?

    • 11 months ago
  4. katrinaaap
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    2 and 3

    • 11 months ago
  5. Mertsj
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    And on your unit circle, what angle has sqrt2/2 for its cosine?

    • 11 months ago
  6. katrinaaap
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    -45

    • 11 months ago
  7. Mertsj
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    45 does have that cosine ut we said we would be in quadrants II and III where the cosine is negative. Also you said your answer had to be between 0 and 2 pi so I think you should give the answer in radians.

    • 11 months ago
  8. Mertsj
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    How many radians is 45 degrees?

    • 11 months ago
  9. katrinaaap
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    45 degrees is pi/4

    • 11 months ago
  10. Mertsj
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    So...in quadrants II and III:

    • 11 months ago
  11. Mertsj
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    |dw:1368665856951:dw|

    • 11 months ago
  12. Mertsj
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    What is the angle meassured from the positive x axis?

    • 11 months ago
  13. katrinaaap
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    135

    • 11 months ago
  14. Mertsj
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    radians, my dear.

    • 11 months ago
  15. katrinaaap
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    3pi/4

    • 11 months ago
  16. Mertsj
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    Yes. And now for the third quadrant answer:

    • 11 months ago
  17. katrinaaap
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    5pi/4

    • 11 months ago
  18. Mertsj
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    |dw:1368666064142:dw|

    • 11 months ago
  19. Mertsj
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    Very good. And now you have your two answers. The angles between 0 and 2 pi that have a cosine of -sqrt2/2 are 3pi/4 and 5pi/4

    • 11 months ago
  20. katrinaaap
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    perfect

    • 11 months ago
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