(i) `sin70^(@)+sec70^(@)=sin(90^(@)-20^(@))+sec(90^(@)-20^(@))=cos20^(@)+"cosec " 20^(@)`
(ii) `tan65^(@)+"cosec " 65^(@)=tan(90^(@)-25^(@))+"cosec"(90^(@)-25^(@))=cot25^(@)+sec25^(@)`
(iii) `cos81^(@)+cot80^(@)=cos(90^(@)=9^(@))+cot(90^(@)-10^(@))=sin9^(@)+tan10^(@)`