(-cos(a/2) + sin(a/2))^2/(1.0 - sin(a))
1 sin(a)
- ----------- + -----------
-1 + sin(a) -1 + sin(a)
$$\frac{\sin{\left (a \right )}}{\sin{\left (a \right )} - 1} - \frac{1}{\sin{\left (a \right )} - 1}$$
/ 2/a\ 2/a\ /a\ /a\\
-|cos |-| + sin |-| - 2*cos|-|*sin|-||
\ \2/ \2/ \2/ \2//
---------------------------------------
-1 + sin(a)
$$- \frac{1}{\sin{\left (a \right )} - 1} \left(\sin^{2}{\left (\frac{a}{2} \right )} - 2 \sin{\left (\frac{a}{2} \right )} \cos{\left (\frac{a}{2} \right )} + \cos^{2}{\left (\frac{a}{2} \right )}\right)$$
Тригонометрическая часть
[src] 2
/ /a\ /a\\
-|- sin|-| + cos|-||
\ \2/ \2//
----------------------
-1 + sin(a)
$$- \frac{\left(- \sin{\left (\frac{a}{2} \right )} + \cos{\left (\frac{a}{2} \right )}\right)^{2}}{\sin{\left (a \right )} - 1}$$