Last updated at May 29, 2018 by Teachoo

Transcript

Ex 3.3, 4 Prove that 2sin2 3 /4 + 2cos2 /4 + 2sec2 /3 = 10 Taking L.H.S 2sin2 3 /4 + 2cos2 /4 + 2sec2 /3 Putting = 180 2 sin2 (3 180/4 ) + 2cos2 (180/4) + 2sec2 (180/3) = 2sin2 (135 )+2 cos2 (45 ) + 2sec2(60 ) Putting values = 2 sin2 (135 ) +2 cos2 (45 ) + 2sec2 (60 ) = 2 (1/ 2)^2 + 2 (1/ 2)^2 + 2 (2)2 = 2 [(1/ 2)^2 " + " (1/ 2)^2 " + 22" ] = 2 [ 1/2 + 1/2 + 4] = 2 [1 + 4] = 2 5 =10 = R.H.S L.H.S. = R.H.S. Hence proved

Finding Value of trignometric functions, given angle

Negative Angle Identities

Value of sin, cos, tan repeats after 2π

Shifting angle by π/2, π, 3π/2 , 2π

Example 8

Ex 3.2, 9 Important

Ex 3.2, 8 Important

Ex 3.2, 10

Example 9

Ex 3.2, 6

Ex 3.2, 7 Important

Example 10

Ex 3.3, 1

Ex 3.3, 2

Ex 3.3, 3

Ex 3.3, 4 Important You are here

Ex 3.3, 8 Important

Ex 3.3, 9

Find values of sin 18, cos 18, cos 36, sin 36, sin 54, cos 54

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.