base from the given that tan X =sin X / cos X. so the answer to the question what is tan ( 90 - A) is:
first let X = 90 - A
substituting from the given that
tan X =sin X / cos X
tan ( 90 - A) = sin ( 90 - A) / cos ( 90 - A)
i hope this can help with your question. feel free to ask frther clarifications
