(13) [a"dx= ex-ex shx= 2 I4)∫shxdx=-chx+C (I5)「ch xdx=shx+C chx= 2 =  a x x (13) d C a a x + ln 2 sh x x e e x − − = ch x +C =  (15) ch xdx sh x +C =  (14) sh xdx 2 ch x x e e x − + =