Lesson1. Exercise.Trigonometric ratios(घर के लिए ट्यूशन रांची )

Class work:

Q1.  Fill in the blanks:

 In the above figure, 

sin A = ....... 

cos A = ....... 

tan A = ....... 

cosec A = .,..... 

sec A = ...,.... 

cot A  = ......, 

sin C = .......

cos C = ......

tan C = ......

cosec C = ....... 

sec C = ........ 

cot C = ........ 

 Q2. If sin A = 8 /17, find the other trigonometric ratios of angle A.

Ans: Let us draw a triangle ABC in which angle B = 90 deg. 

Sin A = p/h = 8/17

Let p = 8k

h = 17k, where k is a positive number. 

                      _______

Hence b = √ h2 - p2 

                   _____________

            = √ 289 k2 - 64 k2

                  _______     

            = √ 225 k2

             = 15 k

Hence

sin A = p/h = 8/17

cos A = b/h  = 15/17

tan A = p/b = 8/15

cosec A = 1/sin A = 17/8

sec A = 1/cos A = 17/15

cot A = 1/tan A = 15/8

Q3. If sin A = 3/5, find the other trigonometric ratios of angle A. 

Ans: cos A = 4/5, tan A = 3/4

Q4. If cos A = 9/41, find the other trigonometric ratios of angle A. 

Ans: sin A = 40/41, cos A = 9/41, tan A = 40/9

Q5. If tan A = √3, find other trigonometric ratios of angle A. 

Ans: sin  A = √3/2, cos A = 1/2

H. W. 

......... 

Q1. If sec theta = 25/7 , find all trigonometric ratios of theta

Ans: sin A = 24/25, cos A = 7/25, tan A = 24/7

Q2. If sin alpha = 1/2, show that

(3cos alpha - 4 cos^3 alpha) = 0