Math

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How many solutions does the equation cosx + 1/2 = 1 have for 0<x<2pi


cosx+1/2=1
cosx+1=2
cosx=2-1
cosx=1

therefore 1 solution?


A) 1
b) 2
c) 3
d) 4

  • Math -

    What did you do ????

    cosx + 1/2 = 1
    cosx = 1/2
    the cosine is positive in quads I and IV
    x = 30° or x = 330° or (π/6 and 11π/6)

    so obviously 2 solutions between 0 and 2π

  • Math -

    How come I am not suppose to get rid of the the denominator?

  • Math -

    if you had multiplied by 2 then your second line should have been

    2cosx + 1 = 2 . and then
    2cosx = 1
    cosx = 1/2 , now pick it up in my solution.

    you forgot to multiply the cosx by 2

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