Trigonometric Prove...1

Discussion in 'Other Pre-University Math' started by nycmathguy, Jan 30, 2022.

  1. nycmathguy

    nycmathguy

    Joined:
    Jun 27, 2021
    Messages:
    5,386
    Likes Received:
    422
    David Cohen

    IMG_20220130_130423.jpg
     
    nycmathguy, Jan 30, 2022
    #1
  2. nycmathguy

    MathLover1

    Joined:
    Jun 27, 2021
    Messages:
    2,989
    Likes Received:
    2,884
    suppose that

    x+1/x=2cos(θ)

    show that x^2+1/x^2=2cos(3θ)

    Given,
    x+1/x=2cos(θ)

    =>(x+1/x)^2=(2cos(θ) )^2

    x^2 + 1/x^2 + 2=4cos^2(θ)

    x^2 + 1/x^2 =4cos^2(θ) -2

    x^2 + 1/x^2 =2(2cos^2(θ) -1)

    x^2 + 1/x^2 =2cos(2 θ)
     
    MathLover1, Jan 30, 2022
    #2
    nycmathguy likes this.
  3. nycmathguy

    nycmathguy

    Joined:
    Jun 27, 2021
    Messages:
    5,386
    Likes Received:
    422
    Thank you. I hope to solve this root tip toothache today. I cannot wait until 2/17. I am literally shedding tears.
     
    nycmathguy, Jan 31, 2022
    #3
Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Similar Threads

  1. Prove Inverse Trigonometric Identities

  2. Prove Inverse Trigonometric Functions

  3. Trigonometric Prove...2

Loading...