Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

lsugano

  • 2 years ago

what is cot2a=0 Thus 2a=90˚....how did this happen?

  • This Question is Closed
  1. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[ cot2a = 0 => \frac{cos2a}{sin2a} = 0 => cos2a = 0 => 2a = cos(0)\]

  2. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    wait i made a typo: \[ 2a = cos^{-1}(0)\]

  3. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    since you know that \(cos^{-1}(0) = 90\)

  4. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    then \( 2a = 90\)

  5. lsugano
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wait how did cot2a= cos2a/sin2a?

  6. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Firstly you should remember that: \[\cos(90) = 0\]

  7. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    because \[ cota = \frac{cosa}{sina}\]

  8. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    *cot

  9. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    \[\large \cot(90^{\circ}) = 0\]

  10. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So you can replace 0 with cot(90): \[\cot(2a) = \cot(90)\]

  11. lsugano
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    im sorry but isnt cot= 1/tana?

  12. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    well you can use that method if you remember whats cot(90)

  13. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Now as trigonometric ratio is same: So you can equate the angles: \[2a = 90\]

  14. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes it because what tana?

  15. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    what is*

  16. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes it is but whats tan(a) then?*

  17. lsugano
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh cot also equals to x/y so cos/sin right??

  18. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Right..

  19. lsugano
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ohhhh okay it makes sense

  20. lsugano
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so i get that cos2a/sin2a = 0 but then what is next?

  21. Mimi_x3
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    i typed the solution for you already..

  22. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Multiply by sin(2a) both the sides..

  23. lsugano
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so it becomes cos2a (sin2a) = 0 (sin2a)

  24. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    No.. There is one sin(2a) in the denominator too..

  25. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Can't you cancel sin(2a) with sin(2a) on left hand side ??

  26. lsugano
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so does it become like this?

    1 Attachment
  27. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yep..

  28. lsugano
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh okay now i get the steps! thank you so much @waterineyes @Mimi_x3

  29. waterineyes
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Welcome dear..

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

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

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.