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Last updated at Feb. 12, 2020 by Teachoo

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Ex 3.2, 10 Find the value of the trigonometric function cot ("โ" 15"ฯ" /4) cot ((โ15 ๐)/4) = โcot ((15 ๐)/4) = โcot ("3" 3/4 "ฯ" ) = โcot ("4ฯ โ " 1/4 " ฯ" ) = โ cot ((โ1)/4 " ฯ" ) Values of cot x repeats after an interval of 2ฯ , Hence ignoring 4ฯ i.e. 2 ร (2ฯ) Rough So, 15/4 = 3 3/4 = 3 + 3/4 or 4 โ 1/4 We take 4 โ 1/4 as it is even = โ("โ cot " (1/4 " ฯ" )) = cot (1/4 " ฯ" ) = cot (1/4 " ร 180" ) = cot 45ยฐ = 1

Finding Value of trignometric functions, given angle

Negative Angle Identities

Value of sin, cos, tan repeats after 2ฯ

Shifting angle by ฯ/2, ฯ, 3ฯ/2 , 2ฯ

Example 8

Ex 3.2, 9 Important

Ex 3.2, 8 Important

Ex 3.2, 10 Important You are here

Example 9 Important

Ex 3.2, 6

Ex 3.2, 7 Important

Example 10

Ex 3.3, 1

Ex 3.3, 2 Important

Ex 3.3, 3 Important

Ex 3.3, 4

Ex 3.3, 8 Important

Ex 3.3, 9 Important

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

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.