A Test Posting

$$ \eqalign{ \alpha &= \arccos{\frac{ (a-b)^2+ d^2 -(c+b)^2}{2 d (a-b)} } \cr \beta &= \arccos{\frac{ (a-b)^2+ (c+b)^2 -d^2}{2 (c+b) (a-b)} } \cr \gamma &= \alpha + \beta \cr s &= a\,\alpha + b\,(\beta+\pi) + c\,\gamma } $$