Question 1155498


{{{2cos(theta)+1=0}}}

{{{2cos(theta)=-1}}}

{{{cos(theta)=-1/2}}}

{{{theta=cos^-1(-1/2)}}}

{{{theta=(2Pi)/3}}}


given: {{{0< theta<360}}}

=>{{{theta=(2Pi)/3}}}, {{{theta=(4Pi)/3}}}

=>{{{theta=120}}}°,  {{{theta=240}}}°