T R I 



given sides for the /'s of the polar A, and the supplements of the giren 

 /'s for the sides. 



Solution of the six cases of oblique d spherical A*. 



Case 1. 

 Given the three sides a, b t c to find A. 



Section 3d. (Ta, * )' = , X -5^-M^d . 



Sometimes one of these methods may be more convenient than ano- 

 ther, see corresponding case in Plane Trigonometry. 



Case 2. 

 Given A, B, C to find a, &c. 



Solution 1st. Let S' = A "*" "*" C , then 



So,uon 3^,=, X-T. 



S' is greater than 90 and less than 270o, .*. cos. S' is positive, and 

 whole quantity is positive. 



Case 3. 

 Given a, ft and included / C. Required A and B. 



a b 

 cos. - 



Solution 1st. Tan. ^--5 = - - Cot. ~ 



^ _^_. Cot 

 sm ^ 



from whence A -f- B and A B, and consequently A and B may be found, 

 as also c. 

 324 



