Last updated at May 29, 2018 by Teachoo

Transcript

Ex 3.3, 23 Prove that tan 4 = (4 tan (1 tan2 ) )/(1 6 tan2 +tan4 ) Taking L.H.S. tan 4x = (2 tan 2x)/(1 tan2 2x) tan 4x = 2((2 tan )/(1 2 ))/(1 ((2 tan )/(1 2 ))^2 ) = (((4 tan )/(1 2 )))/(1 ((2 tan )^2/(1 2 )^2 ) ) = (((4 tan )/(1 2 )))/(1 ((4 ^2 )/(1 2 )^2 ) ) = (((4 tan )/(1 2 )))/((((1 2 )^2 4 ^2 )/(1 2 )^2 ) ) = (4 tan )/(1 tan2 ) ((1 tan2 )2 )/((1 2 )2 4 tan2 ) = (4 tan )/1 ((1 tan2 ) )/((1 2 )2 4 tan2 ) = (4 tan (1 2 ))/((1 tan2 )2 4 tan 2 ) Using (a b)2 = a2 +b2 2ab = (4 tan ( 1 tan2 ) )/(( (1)2+( 2 )2 2 1 2 ) 4 2 ) = (4 tan ( 1 tan2 ) )/(( (1)2+( 2 )2 2 1 2 ) 4 2 ) = (4 tan ( 1 tan2 ) )/(1 + tan 4 2 tan2 4 tan2 ) = (4 tan ( 1 tan2 ) )/(1 + tan4 6 4 ) = R.H.S. Hence L.H.S. = R.H.S. Hence proved

Chapter 3 Class 11 Trigonometric Functions

Concept wise

- Radian measure - Conversion
- Arc length
- Finding Value of trignometric functions, given other functions
- Finding Value of trignometric functions, given angle
- (x + y) formula
- 2x 3x formula - Proving
- 2x 3x formula - Finding value
- cos x + cos y formula
- 2 sin x sin y formula
- Finding Principal solutions
- Finding General Solutions
- Sine and Cosine Formula

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.