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: Trig Identities

  1. Apr 18, 2010 #1
    1. The problem statement, all variables and given/known data
    Verify that each equation is an identity- directions
    Problem- csc(A-B)=secB
    ---------------- <<< divide bar
    2. Relevant equations

    well i tried to put in terms of sin cos and i've gotten stuck

    3. The attempt at a solution

    i started off by disributing i.e.>> cscA-cscB=secB/sinA-cosAtanB
    next i changed tan to sin/cos and cancelled out cos so i was left with cscA-cscB=sec/sinA-sinB

    changed csc to 1/sinA-1/sinB=sec/sinA-sinB

    changed sec to 1/cos so i flipped and multiplied 1/sinA-sinB and got 1/sinA-1/sinB= 1/sincosA-sincosB and im stuck here..... help please
  2. jcsd
  3. Apr 18, 2010 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Just to be clear, the problem you're trying to solve is to verify the identity

    [tex]\csc(A-B)=\frac{\sec B}{\sin A-\cos A \tan B}[/tex]

    right? Your post is kind of hard to read.

    Your very first step is wrong because [itex]\csc(A-B) \ne \csc A - \csc B[/itex]. Try writing it in terms of sin(A-B) first and go from there.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook