See attached questions and answers below from my grade 12 advanced functions text which includes trigonometry. I
understand the question and answer. For future problems, I know that it’s a good idea to break down given angles, i.e., cos (15) into the “remarkable” or “known” angles that are associated with a triangle and then apply the compound angle formulas.
Can someone please provide a list of the remarkable (or most often used in grade 12 Trig) angles please? Please give the angle values in degrees and radians. I searched google but too many hits came up!
If you can provide the name of the triangle the angles are from, that would be greatly appreciated too!