Ask Experts Questions for FREE Help !
Ask
    Faris3's Avatar
    Faris3 Posts: 1, Reputation: 1
    New Member
     
    #1

    Nov 7, 2011, 12:15 PM
    about cos(x)=-1/2
    Hello there. I was having some trouble with a little question.
    If cos(x)= 1/2 then x = arcos(1/2) which is pie/3.
    Now if cos(x)= -1/2, is x=arcos(-1/2) still pie/3 or is arcos(-1/2) = 2pie/3?
    Or are maybe both of them right? Thanks in advance.
    ebaines's Avatar
    ebaines Posts: 12,131, Reputation: 1307
    Expert
     
    #2

    Nov 7, 2011, 12:29 PM
    You are correct that if then , although it could also equal , because . The complete set of solutions is:

    for equals any integer.

    If cos(x) = -1/2 then or . It can't be because we already know that , not .

Not your question? Ask your question View similar questions

 

Question Tools Search this Question
Search this Question:

Advanced Search

Add your answer here.


Check out some similar questions!

(cos x/sec x)-(cos x/tan^2 x)= cot^2 x? [ 3 Answers ]

Verifying/proving of the trigonometric identities


View more questions Search