Posted by Natalie on Sunday, April 7, 2013 at 1:13pm.
I will use 30° and 60° , easier to type cos (x+300) +sin (x-60) = cosxcos30 - sinxsin30 + sinxcos60 - cosxsin60 = (√3/2)cosx - (1/2)sinx + (1/2)sinx - (√3/2)cosx = 0 = RS