If y=2a2-b2tan-1[a-ba+btanx2], a,b>0, dydx|x=π2=
(2)
y=2a2-b2tan-1(a-ba+btanx2)
dydx=2a2-b21(1+a-ba+btan2x2)sec2x2·12a-ba+b
dydx|x=π2=1a