Question 1141668
{{{ sin(x) = -3/4 }}}
{{{ x = arcsin( -3/4 ) }}}
{{{ x = 48.5904 + 180 }}}
{{{ x = 228.5904 }}}
{{{ x/2 = 114.2952 }}}
{{{ cos( 114.2952 ) = -.4114 }}}
Note that {{{ x/2 }}} is in the 2nd quadrant
Get a 2nd opinion if needed