Question 886384
 {{{cos(theta/2)}} = 0}}}

{{{theta/2}}}{{{""=""}}}{{{pi/2}}} or {{{3pi/2}}} 

{{{theta}}}{{{""=""}}}{{{2pi/2}}} or {{{6pi/2}}}}

{{{theta}}}{{{""=""}}}{{{pi}}} or {{{cross(3pi)}}}

We can't use {{{3pi}}} because it's not in the interval {{{(matrix(1,3,0,",",2pi))}}}

The only solution id {{{pi}}}

Edwin</pre