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greeneyes<3

  • 4 years ago

Evaluate without using a calculator. Give answer in radians and degrees. Show work please or explain it!

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  1. greeneyes<3
    • 4 years ago
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    \[\cos^{-1}(-\sqrt{2}/2) \]

  2. dumbcow
    • 4 years ago
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    from the unit circle i know that cos(x) = -sqrt(2)/2 when x = 3pi/4 and 5pi/4

  3. dumbcow
    • 4 years ago
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    convert to degrees.....pi = 180

  4. dumbcow
    • 4 years ago
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    do you need more explanation?

  5. greeneyes<3
    • 4 years ago
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    thank you so its 180 degrees & 3 pi/4 ?

  6. dumbcow
    • 4 years ago
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    ?? no pi radians is equivalent to 180 degrees there are 2 possible answers (2 diff angles satisfy cos(x) = -sqrt2/2) i gave you answers in radians, you have to convert to degrees by replacing pi with 180

  7. dumbcow
    • 4 years ago
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    good reference http://www.mathpeer.com/index.php?act=trigonometry&trig=radian_measure_and_the_circular_functions

  8. greeneyes<3
    • 4 years ago
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    oh... i'm sorry so the answer is 180 degrees & pi ? I don't understand how to get to 180 degrees. :/

  9. dumbcow
    • 4 years ago
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    hmm ok apparently i am only confusing you more just look at the unit circle and find -sqrt2/2, the answers will be the angle measures

  10. greeneyes<3
    • 4 years ago
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    5 pi/4 ?

  11. dumbcow
    • 4 years ago
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    yep thats 1 answer

  12. greeneyes<3
    • 4 years ago
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    i hope i'm not annoying or anything lol you don't have to help me but is the answer for \[\sin^{-1} (-1)\] = 270 degrees, (3 pi/2) ?

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