Question 978388
{{{ tan(u) = -1.582 }}}
{{{ u = arctan ( -1.582 ) }}}
By my calculator:
{{{ u = 180 - 57.7026 }}} degrees
{{{ u = 122.2974 }}}
{{{ u/2 = 61.149 }}} degrees
{{{ cos( 61.149 ) = .4825 }}} 
Hope I got it