Question 1181526
<pre>
{{{sin(expr(1/2)(theta - pi/3)^"")}}}{{{""=""}}}{{{-sqrt(3)/2}}}

The sine is negative in QIII and QIV, so

{{{expr(1/2)(theta - pi/3)}}}{{{""=""}}}{{{matrix(1,3,4pi/3+2pi*n,or,5pi/3+2pi*n)}}}

Multiply through by 2

{{{theta - pi/3}}}{{{""=""}}}{{{matrix(1,3,8pi/3+4pi*n,or,10pi/3+4pi*n)}}}

Add pi/3 to both sides

{{{theta}}}{{{""=""}}}{{{matrix(1,3,9pi/3+4pi*n,or,11pi/3+4pi*n)}}}

{{{theta}}}{{{""=""}}}{{{matrix(1,3,3pi+4pi*n,or,11pi/3+4pi*n)}}}

factor out &pi;:

{{{theta}}}{{{""=""}}}{{{matrix(1,3,pi*(3+4n),or,pi*(11/3+4n))}}}

Edwin</pre>