Homework Help

Prove that: `(1+ sec x)/sec x = (sin^2x)/(1 - cos x)`

user profile pic

chiraagsrt | Student, Grade 10 | eNotes Newbie

Posted May 2, 2012 at 5:33 PM via web

dislike 3 like

Prove that: `(1+ sec x)/sec x = (sin^2x)/(1 - cos x)`

2 Answers | Add Yours

user profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted May 2, 2012 at 5:45 PM (Answer #1)

dislike 1 like

The identity `(1 + sec x)/sec x = (sin^2 x)/(1 - cos x)` has to be proved.

`(sin^2 x)/(1 - cos x)`

=> `(1 - cos^2x)/(1 - cos x)`

=> `((1 - cos x)(1 + cos x))/(1 - cos x)`

=> `(1 + cos x)`

=> `1 + 1/sec x`

=> `(sec x + 1)/sec x`

This proves that `(1 + sec x)/sec x = (sin^2 x)/(1 - cos x)`

user profile pic

malagala | College Teacher | (Level 2) Adjunct Educator

Posted May 2, 2012 at 5:56 PM (Answer #2)

dislike 1 like

=> (1 +sec x) / (sec x)

=> ( 1+ (1/cos x)) / (1/cosx)

musltply each term by cos x

=> (cos x + 1) / 1

multiply both numerator and the denominator by (1- cos x)

=> (1 + cos x)(1- cos x) / (1-cos  x)

=> (1 - cos^2x) / (1- cos x)

 as cos ^2x + sin ^2x = 1,

     1 - cos ^2 x = sin^2 x

substituting this,

=>sin^2x /( 1- cosx)

hence (1 +sec x) / (sec x) = sin^2x /( 1- cosx)


Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes