Question

How do you verify that the x values `pi/3, (5pi)/3` are solutions to `2cosx-1=0`?

Answer 1

Use trig table of special arcs -->
When `x = pi/3` --> `cos (pi/3) = 1/2`
`2cos x - 1 = 2/2 - 1 = 0`. Proved

When `x = (5pi)/3` --> `cos ((5pi)/3) = cos (pi/3) = 1/2`
`2cos x - 1 = 2/2 - 1 = 0`. Proved