limx→π2cos2 x1−sin x
=limx→π21−sin2 x1−sin x=limx→π2(1−sin x)(1+sin x)(1−sin x)
=limx→π2(1+sin x)
=1+sinπ2
=1+1 =2
limx→π2√2−sin x−1(π2−x)2
limx→π2√2−√1+sin xcos2 x