Kannappan, P. A functional equation for the cosine. (English) Zbl 0165.50003 Can. Math. Bull. 11, 495-498 (1968). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 17 Documents Keywords:functional analysis × Cite Format Result Cite Review PDF Full Text: DOI