What is the equation used for obtaining R value in terms of HSI compo

1.	What is the equation used for obtaining R value in terms of HSI components?
A.	R=I[1-(S cos⁡H)/cos⁡(60°-H) ].
B.	R=I[1+(S cos⁡H)/cos(120°-H)].
C.	R=I[1+(S cos⁡H)/cos⁡(60°-H) ].
D.	R=I[1+(S cos⁡H)/cos(30°-H) ].
Answer» D. R=I[1+(S cos⁡H)/cos(30°-H) ].

Discussion