[.0,(PI / 4).] c= [.0,(PI / 2).[ by Lm5, XXREAL_2:def 12;
then sec | [.0,(PI / 4).] is increasing by Th17, RFUNCT_2:28;
hence (sec | [.0,(PI / 4).]) | [.0,(PI / 4).] is increasing ; :: thesis: verum