cos(-585°)/sin630°+sin( -690°)
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cos(-585°)/sin630°+sin( -690°)
=cos(720°-585°)/sin(720°-90°)+sin(720° -690°)
=cos135°/(-sin90°)+sin30°
=cos(180°-45°)/(-sin90°)+sin30°
=-cos45°/(-sin90°)+sin30°
=cos45°/sin90°+sin30°
=√2/2+1/2
=cos(720°-585°)/sin(720°-90°)+sin(720° -690°)
=cos135°/(-sin90°)+sin30°
=cos(180°-45°)/(-sin90°)+sin30°
=-cos45°/(-sin90°)+sin30°
=cos45°/sin90°+sin30°
=√2/2+1/2
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