Consider the triangle, having the angles  and sides  as shown in the figure.
1) Law of Sine is
2) Laws of Cosine are
             or                       or                               or
3) Laws of Tangent are
           
           
           
HALF ANGLE FORMULAS
            Consider that  and  are sides and angles of , as shown above, also if

(i)  (ii)
4)  
5)
6)
7)
8)
9)
10)
11)
12)