Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Avenged7x

  • one year ago

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

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

    idk even where to begin

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

    Memorize the identities for cos 2*theta

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

    One way to find out is to find a counterexample

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

    try theta=pi/2 does not work

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

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

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

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

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

    Maybe the problem has been written incorrectly.

  11. myininaya
    • one year 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
    • one year 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

Sign Up
Find more explanations on OpenStudy
Privacy Policy