Plane trigonometry. An elementary course, excluding the use of imaginary quantities 2026-02-15T08:22:07+03:00 DEBUG: VuFind\ILS\Driver\Folio: Token taken from global cache: eyJhbGciOiJIUzI1NiJ9.eyJzdWIiO... - Loney, S. L. (A.I.T.B.S. Publ., 2007)