`int sec x log (sec x + tan x) dx ` का माना ज्ञात कीजिये |

Explanation

माना `I = int sec x log (sec x tan x) dx`
माना `log (secx +tanx) = t`
`therefore " "((sec x tan x + sec^(2) x)dx)/((sec x +tan x)) = dt`
`(sec x(sec x +tan x))/((secx +tanx)) dx = dt`
`rArr" " sec x dx = dt`
`therefore I = int t dt = (1)/(2)t^(2) = (1)/(2)[ log (sec x + tan x)]^(2)`