cos(-585°)/[sin495°+sin(-570°)]
=cos(135°-720°)/[sin(135°+360°)+sin(150°-720°)]
=cos135°/(sin135°+sin150°)
=(-根号2/2)/(根号2/2 +1/2)
=(-根号2)/(根号2 +1)
=(-根号2)(根号2 -1)
=-2+根号2
(=根号2 -2)
cos(-585°)/[sin495°+sin(-570°)]
=cos(135°-720°)/[sin(135°+360°)+sin(150°-720°)]
=cos135°/(sin135°+sin150°)
=(-根号2/2)/(根号2/2 +1/2)
=(-根号2)/(根号2 +1)
=(-根号2)(根号2 -1)
=-2+根号2
(=根号2 -2)