Question 927958
solution posted below
*[illustration solution_927958].
hope this helps!

Response to comment:
Since they're asking for a third answer ask again, when does cos(z)=1/2?
cos(z) would equal 1/2 when z equals {{{7pi/3}}}
Plug into the equation: 3x=z
{{{3x=7pi/3}}}
{{{x=7pi/9}}}
Since the equation's domain is up to {{{pi}}}, this is why they ask for the third solution. The next solution for x would be {{{11pi/9}}} but this is wrong since {{{11pi/9}}} is greater than {{{pi}}}. {{{11pi/9}}} exceeds the domain restrictions.