Question 594088
cos(45) + cos(15)


cos(30+15) + cos(30-15)


2*cos(30)*cos(15)


2*(sqrt(3)/2)*cos(15)


sqrt(3)*cos(15)



So <img src="http://latex.codecogs.com/gif.latex?\large \cos(45) + \cos(15) = \sqrt{3}\cos(15)" title="x" />