∫ P ( 1 + , 0 + , 1 - , 0 - ) t a - 1 ( 1 - t ) b - 1 d t = - 4 e π i ( a + b ) sin ( π a ) sin ( π b ) B ( a , b ) \int_{P}^{(1+,0+,1-,0-)}t^{a-1}(1-t)^{b-1}\mathrm{d}t=-4e^{\pi i(a+b)}\sin\left(\pi a\right)\sin\left(\pi b\right)\mathrm{B}\left(a,b\right)