1. The problem statement, all variables and given/known data Find the values of the following, without the use of a calculator, cos(15)+sin(15) 2. Relevant equations sin(A±B)= sinAcosB±cosAsinB cos(A±B)= cosAcosB∓sinAsinB 3. The attempt at a solution Without the use of a calculator i had to relate back to the 2 triangles which you get the most common values for sin, cos and tan. Namely, sin(30)= 1/2 cos(30)= √3/2 sin(45)= 1/√2 cos(45)= 1/√2 sin(60)= √3/2 cos(60)= 1/2 sin(0)= 0 cos(0)= 1 sin(90)=1 cos(90)= 0 but i have found no use for any of these, also i didnt think tan was appropriate but im open to correction!! i tried going along the lines of gettting a trig function, with the same angle, to equal 1 so i could use the addition formulae but i had no success! any help please guys!!