Question

Find all values of x in the interval [0, 2π] that satisfy the equation. (Enter your answers as a comma-separated list.)? 18 cos(x) − 9 = 0

Answer 1

`x=pi/3, (5pi)/3`

Explanation:

First isolate X:
`18cosx-9=0`
`18cosx=9`
`cosx=9/18`
`cosx=1/2`
Now that we know that Cosine of X =`1/2`, we can use the unit circle to find which angles satisty the equation.
Points on the unit circle are `(cos, sin)`, so any point on the unit circle that has an x value of `1/2` is a solution. The angles that satisfy this condition are `pi/3` and `(5pi)/3`.