Question 975571
{{{sin(3*theta)=-1}}}
{{{3*theta=(3/2)pi}}}
{{{theta=pi/2}}}
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{{{cos(2*theta)=-1/2}}}
{{{2*theta=(2/3)pi}}} and {{{2*theta=(4/3)pi}}}
{{{theta=pi/3}}} and {{{theta=(2/3)pi}}}