# Ex 7.3, 3 - Chapter 7 Class 12 Integrals

Last updated at July 11, 2018 by Teachoo

Last updated at July 11, 2018 by Teachoo

Transcript

Ex 7.3, 3 cos 2x cos 4x cos 6x We know that 2 cos A cos B= cos + + cos Replace A by 2 & B by 4 2 cos 2 cos 4 = cos 2 +4 + cos 2 4 2 cos 2 cos 4 = cos 6 + cos 2 2 cos 2 cos 4 = cos 6 + cos 2 cos 2 cos 4 = 1 2 cos 6 + cos 2 cos 2 cos 4 cos 6 = 1 2 cos 6 + cos 2 cos 6 = 1 2 cos 6 + cos 2 cos 6 = 1 2 cos 6 2 + cos 2 . cos 6 = 1 2 cos 6 2 + cos 2 . cos 6 Now, cos 2 cos 4 cos 6 = 1 2 cos 2 6 + 2 cos 6 = 1 2 1 2 12 +1 + 1 2 8 + cos 4 = 1 4 12 +1 + ( 8 + cos 4 ) = 1 4 12 + 1 + cos 8 + cos 4 = + + + +

Integration using trigo identities - CD and CD inv formulae

Chapter 7 Class 12 Integrals

Concept wise

- Using Formulaes
- Using Trignometric Formulaes
- Integration by substitution - x^n
- Integration by substitution - lnx
- Integration by substitution - e^x
- Integration by substitution - Trignometric - Normal
- Integration by substitution - Trignometric - Inverse
- Integration using trigo identities - sin^2,cos^2 etc formulae
- Integration using trigo identities - a-b formulae
- Integration using trigo identities - 2x formulae
- Integration using trigo identities - 3x formulae
- Integration using trigo identities - CD and CD inv formulae
- Integration using trigo identities - Inv Trigo formulae
- Integration by parts
- Integration by parts - e^x integration
- Integration by specific formulaes - Formula 1
- Integration by specific formulaes - Formula 2
- Integration by specific formulaes - Formula 3
- Integration by specific formulaes - Formula 4
- Integration by specific formulaes - Formula 5
- Integration by specific formulaes - Formula 6
- Integration by specific formulaes - Formula 7
- Integration by specific formulaes - Formula 8
- Integration by specific formulaes - Method 9
- Integration by specific formulaes - Method 10
- Integration by partial fraction - Type 1
- Integration by partial fraction - Type 2
- Integration by partial fraction - Type 3
- Integration by partial fraction - Type 4
- Integration by partial fraction - Type 5
- Definite Integral as a limit of a sum
- Definite Integration - By Formulae
- Definite Integration - By Partial Fraction
- Definite Integration - By e formula
- Definite Integration - By Substitution
- Definite Integration by properties - P2
- Definite Integration by properties - P3
- Definite Integration by properties - P4
- Definite Integration by properties - P6
- Definite Integration by properties - P7

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.