Millard R. Mamhot ; Joemar C. Endam ; Alice A. Mamhot ; Emelyn C. Banagua and Jenette S. Bantug <br/><br/>
Plane and Spherical Trigonometry :  A Tetrahedron Approach / 
Mamhot, Millard R. 
 - Intramuros, Manila :  Unlimited Books Library Services & Publishing Inc.,  c2015. 
 - 214 pages:  illustrations ;  23 cm. 
<br/><br/> Includes index and bibliographical references 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Plane trigonometry<br/>Spherical trigonometry<br/>Trigonometry<br/>Mathematics