The greatest among sin1+cos1,sin1+cos1,sin1−cos1and 1 is
sin1+cos1
sin1−cos1
1
We have
0<x<1⇒x2<x
sin1>sin1>sin21;cos1>cos1>cos21 Adding sin1+cos1>sin1+cos1 >sin21+cos21 ⇒sin1+cos1>sin1+cos1>1