A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

please help... calc will be the death of me lol

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    1 Attachment
  2. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @ikram002p heyy any idea here lol

  3. idku
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    this is calculus, are you sure?

  4. idku
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1440615503189:dw|

  5. idku
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    sin(30)=1/2 mutliply both sides times -1 and use the rule -sin(k)=sin(-k)

  6. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wait so how did you decide to do sin 30

  7. idku
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    As for your second problem |dw:1440615688714:dw|

  8. idku
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    how you decide to do for sin(30)? what do you want to know?

  9. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    lets just work on the first one im wayy too lost lol so you drew a reference triangle?

  10. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    when you have negative values of a trig ratio you might find it easier to remember their signs in the 4 quadrants 0 - 360 degrees

  11. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1440615941625:dw|

  12. dumbcow
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    google unit circle

  13. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    so they are ALL positive in first quadrant (0 to 90 degrees) Only the sine is positive in 2nd quadrant, only the tangent in the third and only the cosine in the 4th quadrant - otherwise they are negative

  14. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay i get that

  15. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    so if you have sine x = -0.5 Sine 30 is 0.5 ( thats first quadant) its negative in 2nd and 3rd so 2 values for the angle would be 180-30 = 150 and 180+ 30 = 210 these are the results if the question asks for values of the angle in range 0 to 360 degrees.

  16. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    oh i messed up there sorry! sine is negative in 3rd and 4th quadrants so thats 210 and 330 dgrees!!

  17. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    phew i got nervous for a sec i was like wuttt... but i get that so far

  18. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1440616444926:dw|

  19. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1440616515975:dw|

  20. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    personally i find it easier to use pictures with these problems.

  21. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    theres 2 triangles worth remembering the one that idku posted and also the 45-45-90 triangle

  22. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1440616730872:dw|

  23. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    alrigh but for this [prob im dealing with the 30 60 90

  24. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    2 cos x = sqrt3 cos x = sqrt3/2 so what is the value of angle x ( from the 30 60 90 triangle)?

  25. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    remember cosine = adjacent / hypotenuse

  26. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    maybe the presence of the S is confusing you ?

  27. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so would i tak inverse cos (sqrt3/2) to find the angle

  28. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes - or you can see it on the diagram |dw:1440617639361:dw|

  29. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    when i do it the way i said i get a domain error

  30. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wait can we stick with #1 for now im trying to understand it

  31. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so i get how you found 210 and 330

  32. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1440617866896:dw|

  33. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    when you have time, you might want to review https://www.khanacademy.org/math/trigonometry/unit-circle-trig-func/Trig-unit-circle/v/unit-circle-definition-of-trig-functions-1

  34. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ignore that drawing. i just watched a tutorial. so the question is asking me for the angle measure correct?

  35. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    personally I would solve this \[ \sin x = - \frac{1}{2} , \text{ for } 0 \le x \lt 2 \pi\] but graphing (sketching actually) sin x from 0 to 2pi |dw:1440619769364:dw|

  36. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    looking at the curve, it should be clear there are two angles where sin x = -1/2 we should have memorized some "standard angles" in particular sin 30º = 1/2 thus the solutions will be 30º *in the correct quadrants* in particular 180+30 =210 (but put in radians) and 360-30 = 330º, but put in radians.

  37. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    for 2 cos x = sqr(3) \[ \cos x = \frac{\sqrt{3}}{2} \] |dw:1440620036903:dw| again, two solutions we should know cos 30º = sqr(3)/2 thus 30 and 360-30 = 330º

  38. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay i understand much bette. the way i learned from the tutorial is to isolate the x and then look for it on the unit circle to find possible soulutions and then determine the correct quadrants

  39. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes, that will work also.

  40. freckles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1440621102930:dw|

  41. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.