Test Index

NCERT Class XI Mathematics - Trigonometric Functions - Solutions

© examsnet.com
Question : 40
Total: 61
tan 4x =
4tanx(1−tan2x)
1−6tan2x+tan4x
Solution:  
We have, L.H.S. = tan 4x = tan2(2x)
=
2tan2x
1−tan2x
Since tan 2θ =
2tanθ
1−tan2θ
=
2[
2tanx
1−tan2x
]
1−[
2tanx
1−tan2x
]2
 =
4tanx
1−tan2x
 ×
(1−tan2x)2
(1−tan2x)2−4tan2x
=
4tanx(1−tan2x)
1+tan4x−2tan2x−4tan2x
 =
4tan(1−tan2x)
1−6tan2x+tan4x
 = R.H.S.
© examsnet.com
Go to Question:
Prev Question
Next Question