Last updated at May 29, 2018 by Teachoo

Transcript

Ex 3.3, 9 Prove cos (3 /2+ ) cos (2 + )[cot (3 /2 ) + cot (2 + )] =1 Taking L.H.S. First we solve cos (3 /2 "+ " ) Putting = 180 = cos ((3 180 )/2 " + x" ) = cos ( 270 + x ) = cos ( 360 90 + x ) = cos (2 90 + x ) = cos (2 + (x 90 )) = cos (x 90 ) = cos ( (90 x)) = cos (90 x) = sin x Now cos (2 + x) = cos x & cot (2 + x) = cot x Now we solve cot (3 /2 " " x) Putting = 180 = cot ((3 180 )/2 " x" ) = cot ( 270 " " x ) = cot ( 360 90 " " x ) = cot (2 " " 90 " " x ) = cot (2 " " (x + 90 )) = " " cot (x + 90 ) = ( tan x) = tan x Now putting values in equation cos (3 /2+ ) cos (2 + )[cot (3 /2 ) + cot (2 + )] = (sin x) (cos x) [tan x + cot x] = (sin x cos x) [cot x + tan x] = (sin x cos x) [cos /sin " " + sin /cos ] = (sin x cos x) [( (cos ) (cos )+ (sin ) (sin ))/(sin (cos ))] = (sin x cos x) [(cos2 + sin2 )/(sin (cos ))] = cos2 + sin2 = 1 = R.H.S Hence proved

Ex 3.3, 1

Ex 3.3, 2

Ex 3.3, 3

Ex 3.3, 4 Important

Ex 3.3, 5 Important

Ex 3.3, 6

Ex 3.3, 7

Ex 3.3, 8 Important

Ex 3.3, 9 You are here

Ex 3.3, 10

Ex 3.3, 11 Important

Ex 3.3, 12

Ex 3.3, 13

Ex 3.3, 14

Ex 3.3, 15

Ex 3.3, 16

Ex 3.3, 17

Ex 3.3, 18 Important

Ex 3.3, 19

Ex 3.3, 20

Ex 3.3, 21 Important

Ex 3.3, 22

Ex 3.3, 23 Important

Ex 3.3, 24

Ex 3.3, 25

Chapter 3 Class 11 Trigonometric Functions

Serial order wise

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.