Cos(60-B) + cos (60+B) ———————————- = Sin (60-B) + sin (60-B)

Cos ( 60 – b ) + cos (60 + b)
= cos 60 cos b + sin 60 sin b + cos 60 cos b – sin 60 sin b
= 1/2 cos b + √3/2 sin b + 1/2 cos b – √3/2 sin b
= 1/2 cos b + 1/2 cos b
= cos b

sin ( 60 – b ) + sin ( 60 + b)
= sin 60 cos b – cos 60 sin b + sin 60 cos b + cos 60 sin b
= √3/2 cos b – 1/2 sin b + √3/2 cos b + 1/2 sin b
= √3 cos b

maka cos ( 60 – b ) + cos (60 + b) / sin ( 60-b) + sin (60 + b) = cos b/√3cos b = 1/√3