令x=sint ,dx=costdtt (0到pi/2) pi表示圆周率P=∫（dx）/（x+（1-x^2)^1/2)dx=∫(0到pi/2) costdt/(sint+cost)令t=pi/2-mP=∫(pi/2到0)sinmd(-m)/(cosm+sinm)=∫(0到pi/2) sintdt/(cost+sint)两式相加所以2P==∫(0...