Schaum's outline of precalculus by Safier, Fred

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A basic approach to precalculus trigonometry preparing to succeed in calculus by Kim, Young H., Kim, Youngsoo, Tameru, Ana, Yan, Wen

Plane & spherical trigonometry a tetrahedron approach by Mamhot, Millard R., Endam, Joemar C., Mamhot, Alice A., Banagua, Emelyn C., Bantug, Jenette S.

Worktext in college trigonometry by Domingo, Alleli C., Dimasuay, Lynie B., Lawas, Vernel M., Lubag, Sharon P., Almonte, Velimor D.

Plane trigonometry by Carpio, Joy N., Guillermo, Jaymie M.

Plane and spherical trigonometry text / workbook by Baltazar, Ethel Cecille M., Dy, Ana Liza M., Vidar, Melvin A.

Trigonometry a worktext by Calingasan, Recto Rex M.

Spherical trigonometry a comprehensive approach by Fajardo, Ira A.

Plane and spherical trigonometry by Catolos, Elvira C., Feniquito, Iryne A., Amado, Ma. Victoria P., Avecilla, Leni A., Alba, Ma. Cristina S., Valderama, Julius S.

Schaum's outlines : trigonometry with calculator-based solutions by Moyer, Robert E