Question

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

Answer 1

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

Answer 2

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

Answer 3

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