Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

sabika13 Group Title

How do I solve this trig identity: cos2x/(1+sinx^2)=tan(pie/4 -x)

  • 2 years ago
  • 2 years ago

  • This Question is Closed
  1. matricked Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    i think ur question is cos2x/(1+sin2x) now cos2x =cos^2x -sin^2x=(cosx+sinx)(cosx-sinx) and 1+sin2x = cos^2x + sin^2x +2sinxcosx =(cosx+sinx)^2 thus cos2x/(1+sinx)^2= (cosx+sinx)(cosx-sinx)/(cosx+sinx)^2 =(cosx- sinx)/((cosx+sinx) divide both num and denom by cosx and then we have =(1-sinx/cosx)/(1+sinx/cosx) =(1-tanx)/(1+tanx) = (tan(pi/4) -tanx)/(1+tan(pi/4)tanx)=tan(pie/4 -x)

    • 2 years ago
  2. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    for the second last step.. where did the square roots go? isnt it suppose to be: (1-sinx/cosx)(1-sinx/cos)/(1+sinx/cos)(1+sinx/cosx)

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

    actually the factors (cosx+sinx) are there both in num and denom hence they cancel each other

    • 2 years ago
  4. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    but its (cosx-sinx) in the num :s

    • 2 years ago
  5. matricked Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    (cosx+sinx)(cosx-sinx) / (cosx+sinx)^2 =(cosx-sinx) / (cosx+sinx)

    • 2 years ago
  6. matricked Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    i hope its clear now

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

    why 13 u hv included in ur id ? if u don't mind

    • 2 years ago
  8. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    if its (cosx+sinx)^2, it has to equal (cosx+sinx)(cosx+sinx)

    • 2 years ago
  9. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    idk random.

    • 2 years ago
  10. matricked Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    (cosx+sinx)^2= (cosx+sinx)(cosx+sinx) (correct ) that is why one of the (cosx+sinx)

    • 2 years ago
  11. matricked Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    cancel each other

    • 2 years ago
  12. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    how does cos^2x -sin^2x=(cosx+sinx)(cosx-sinx)

    • 2 years ago
  13. matricked Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    USE ..A*A -B*B =(A)^2 -(B)^2 = (A+B)(A-B)...

    • 2 years ago
  14. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    okay, then why isnt :(cosx+sinx)^2 --> (cosx-sinx)(cosx+sinx)

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

    bcoz a^2 =a*a

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

    so (a+b)^2 =(a+b)(a+b)

    • 2 years ago
  17. matricked Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    but if u multiply (a+b)(a-b) u get (a^2 -b^2)

    • 2 years ago
  18. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    so (a^2-b^2) does not equal (a-b)^2 ?

    • 2 years ago
  19. matricked Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    sahi hai..

    • 2 years ago
  20. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    oh i get it..

    • 2 years ago
  21. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    =(1-tanx)/(1+tanx) = (tan(pi/4) -tanx)/(1+tan(pi/4)tanx)=tan(pie/4 -x) can u explain that? .. where did pi/4 come from ?

    • 2 years ago
  22. Dido525 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Tan (pi/4) = 1.

    • 2 years ago
  23. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    is that a trig identity?

    • 2 years ago
  24. Dido525 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    No. If you do that on a calculator you get that.

    • 2 years ago
  25. Dido525 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Tan(pi/4) is always 1. Look on a unit circle.

    • 2 years ago
  26. sabika13 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Okay, thanks!!

    • 2 years ago
  27. Dido525 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Welcome :) .

    • 2 years ago
    • Attachments:

See more questions >>>

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.