SHASHANK N K
Active member
 |  Subject: P.T. L.H.S.=R.H.S. Wed Jan 30, 2008 12:41 pm | |
| P.T. L.H.S.=R.H.S. :-
(tan A+sec A-1) / (tan A-sec A+1)=(1+sin A)/cos A |
|
abhas
Active member
| | Subject: [ICSE MATHS TRIGNOMERY QUESTION] Wed Jan 30, 2008 9:09 pm | |
| [ICSE MATHS TRIGNOMERY QUESTION]
To prove (tan A+sec A-1) / (tan A-sec A+1) = (1+sin A)/cos A
L.H.S. =
(tan a + sec a -1)/(tan a -sec a + 1)
[substituting -1=-sec2a + tan2 a]
=(tan a+ sec a - sec2a + tan2 a)/(tan a -sec a + 1)
=(tan a+ sec a + (tan a+ sec a)( tan a - sec a))/(tan a -sec a + 1)
=( tan a+ sec a)( tan a - sec a + 1) /(tan a -sec a + 1)
= ( tan a+ sec a) ( tan a - sec a + 1) / (tan a -sec a + 1)
= tan a+ sec a
[but tan a=(sin a/cos a) and sec a=(1/ cos a)]
=(sin a/cos a) + (1/ cos a)
=(sin a + 1)/cos a
this one is my favorite trigonometry question  |
|
India News 
