# 莫尔魏德公式

${\displaystyle {\frac {a+b}{c}}={\frac {\cos \left({\frac {\alpha -\beta }{2}}\right)}{\sin \left({\frac {\gamma }{2}}\right)}}}$

${\displaystyle {\frac {a-b}{c}}={\frac {\sin \left({\frac {\alpha -\beta }{2}}\right)}{\cos \left({\frac {\gamma }{2}}\right)}}.}$

## 参考

1. ^ Ernest Julius Wilczynski, Plane Trigonometry and Applications, Allyn and Bacon, 1914, page 102
2. ^ Michael Sullivan, Trigonometry, Dellen Publishing Company, 1988, page 243.
3. ^ Ernest Julius Wilczynski, Plane Trigonometry and Applications, Allyn and Bacon, 1914, page 105

## 更多阅读

• H. Arthur De Kleine, "Proof Without Words: Mollweide's Equation", Mathematics Magazine, volume 61, number 5, page 281, December, 1988.