TRIGONOMETRICAL FUNCTION
\tɹˌɪɡənə͡ʊmˈɛtɹɪkə͡l fˈʌŋkʃən], \tɹˌɪɡənəʊmˈɛtɹɪkəl fˈʌŋkʃən], \t_ɹ_ˌɪ_ɡ_ə_n_əʊ_m_ˈɛ_t_ɹ_ɪ_k_əl f_ˈʌ_ŋ_k_ʃ_ə_n]\
Sort: Oldest first

(Math.) If an angle is supposed to be at the base of a rightangled triangle,its trigonometrical functions are the ratios of the sides ; viz. the sine, the ratio of perpendicular to hypotenuse ; the tangent, the ratio of perpendicular to base ; the secant, the ratio of hypotenuse to base ; the cosine, cotangent, cosecant, are the same function of the complement of the angle. The definitions apply strictly to an acute angle only, but they admit of extension to angles of all magnitudes. There is another and an older way of defining these functions, according to which they are treated as lines, and called the Trigonometrical lines.
By Henry Percy Smith
Word of the day
mourning cloak
 of temperate regions; having dark purple wings with yellow borders