1.0 业 不 △sin0 0.8 0 uls 0.6 △0→ 0.4- 0.2- 0.0 0 20 40 60 80 0(degrees) △d △元 △0cos0 The fractional error approaches d λ sinO zero as 0 approaches 90o.     sin  cos     d d The fractional error approaches zero as  approaches 90 o