Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Avenged7x

  • 4 months ago

Prove: sin θ - sin θ•cos2 θ = sin3 θ. You must show all work.

  • This Question is Closed
  1. Avenged7x
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 0

    idk even where to begin

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

    Just thought Maybe you can take the right hand side and show the left hand side Try to play with this thought: sin(3x) is sin(2x+x)

  3. myininaya
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 1

    That should be a hint to use the sum identity for sin

  4. Idealist10
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Memorize the identities for cos 2*theta

  5. myininaya
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Though I could be wrong but I don't think this is an identity.

  6. myininaya
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 1

    One way to find out is to find a counterexample

  7. myininaya
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 1

    try theta=pi/2 does not work

  8. Idealist10
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 0

    sin(2x)=2*sin(x)*cos(x)

  9. Idealist10
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 0

    cos(2x)=2cos^2 (x)-1

  10. myininaya
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Maybe the problem has been written incorrectly.

  11. myininaya
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Unless the instructions say to: Prove if true and give a counterexample if false. If so then I have accidentally given you the answer.

  12. Idealist10
    • 4 months ago
    Best Response
    You've already chosen the best response.
    Medals 0

    cos(2x)=1-2sin^2 (x) so what's sin(x)*cos(2x)?

  13. 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.