if sec theta+tan theta+1= 0,then find sec theta -tan theta

sec theta + tan theta +1 =0
sec theta + tan theta = -1 ..............(1)
we know that sec² - tan ² = 1
therfore   (sec+tan)(sec-tan) = 1
                   -1(sec-tan) = 1..........(from 1)
                       sec-tan=1/-1
         therefore sec-tan=-1
Hope it helps.......Cheers!!!