Stitz/Zeager Trigonometry, 3rd Edition Corrected — a free, openly-licensed (CC BY-SA) standalone trigonometry textbook by Carl Stitz and Jeff Zeager, extracted from the full Stitz/Zeager Precalculus volume. Eight-chapter scope mirrors the COD-adopted Lial Trigonometry 12e parent: foundations of trigonometry, the unit-circle and right-triangle definitions, graphs of trigonometric functions, applications and analytic trigonometry, complex numbers and polar coordinates, vectors and parametric equations.
Angles in degrees/minutes/seconds, angle relationships and similar triangles, definitions of the six trigonometric functions, and using the definitions with reciprocal/quotient/Pythagorean identities.
Right-triangle definitions of trigonometric functions, function values for non-acute angles via reference angles, calculator approximations, and applications of right triangles including bearing.
Radian measure, applications including arc length and area of a sector, the unit circle definition of circular functions, and linear and angular speed.
Graphs of sine, cosine, tangent, cotangent, secant, and cosecant; amplitude, period, phase shift, and translations.
Fundamental identities, strategies for verifying identities, sum and difference identities for cosine, sine, and tangent, double-angle identities, and half-angle identities.
Inverse trigonometric functions and their graphs, solving trigonometric equations using algebraic and identity-based methods, and equations involving inverse trigonometric functions.
Oblique triangles solved with the Law of Sines and Law of Cosines, the ambiguous case, geometrically and algebraically defined vectors, and the dot product.
Complex numbers, trigonometric (polar) form of complex numbers, products and quotients of polar-form complex numbers, De Moivre's Theorem, and polar equations and graphs.