1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Trigonometry inequality

  1. Oct 7, 2016 #1
    1. The problem statement, all variables and given/known data
    show that 1-t^2/2 <=cos(t) <=1 for 0<=t<=1

    2. Relevant equations
    Trigonometry knowledge

    3. The attempt at a solution
    I don't know how to relate t with cos(t), and I also try to find out cos(1), but there is no result, so how can I start with this problem.
  2. jcsd
  3. Oct 7, 2016 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Are you sure that it's 0 ≤ t ≤ 1 , and not 0 ≤ t ≤ π/2 ?
  4. Oct 7, 2016 #3
    Yes, this is what the question said. How can you solve for 0 <= t <= pi/2 ?
  5. Oct 7, 2016 #4
  6. Oct 7, 2016 #5


    Staff: Mentor

    Have you know about Maclaurin series yet, and in particular, the Maclaurin series for cos(t)?

    From another question you posted, you are taking a calculus class. If so, both questions should have been posted in the Calculus & Beyond section, not the Precalculus section.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted