This class 10 Maths extra question is from chapter 8 of NCERT text book - Introduction to Trigonometry. Concept Tested: Trigonometric values of basic angles.

Question 13: Find the value of x in each of the following.

(i) cosec 3x = \\frac{\text{cot 30° + cot 60°}}{\text{1 + cot 30° cot 60°}})

(ii) cos x = 2 sin 45° cos 45° – sin 30°

online.maxtute.com

cot 30° = √3 ; cot 60° = \\frac{1}{\sqrt{3}})

\\frac{\text{cot 30° + cot 60° }}{\text{1 + cot 30° cot 60° }}) = \\frac{\sqrt{3}+ \frac{1}{\sqrt{3}}}{1 + \sqrt{3} × \frac{1}{\sqrt{3}}}) = \\frac{\frac{(3+1)}{\sqrt3}}{2})

= \\frac{4}{\sqrt{3}}) × \\frac{\text{1}}{\text{2}})= \\frac{\text{2}}{\sqrt{3}})

So, cosec 3x = \\frac{2}{\sqrt{3}})

We know \\frac{\text{2}}{\sqrt{3}}) = cosec 60°

cosec 3x = cosec 60°

∴ 3x = 60° or x = 20°

sin 45° = cos 45°= \\frac{\text{1}}{\sqrt{2}}) ; sin 30° = \\frac{\text{1}}{\text{2}})

cos x = 2 sin 45° cos 45° – sin 30°= [ 2 × \\frac{\text{1}}{\sqrt{2}}) × \\frac{\text{1}}{\sqrt{2}}) ]- \\frac{1}{2})

cos x = 1 - \\frac{\text{1}}{\text{2}}) = \\frac{\text{1}}{\text{2}})

We know cos 60° = \\frac{\text{1}}{\text{2}})

∴ cos x = cos 60° or **x = 60° **

Class 10 Maths

Register in 2 easy steps and

Start learning in 5 minutes!

CBSE Class 10 Maths - 2021

- Real Numbers Revision Class
- Polynomials Revision Videos
- Linear Equations Revision Class
- Quadratic Equations Revision Class
- Arithmetic Progressions Revision Video
- Triangles Revision
- Coordinate Geometry Revision
- Trigonometry Revision Class
- Appl of Trigonometry
- Circles Revision Class
- Areas Related to Circles Revision Videos

1. Trigonometric Ratios | CBSE Class 10 Extra Practice Question #01 | Easy Question ** Questions 1 ** ▶

2. Trigonometric Ratios | CBSE Class 10 Math Additional Practice Question #02 | Easy Question ** Question 2** ▶

3. Trigonometric values | CBSE Class 10 Math Extra Question #03 | Medium Question ** Question 3** ▶

4. Trigonometry theory & practice | CBSE 10th Extra Practice Question #04 | Medium Question ** Question 4** ▶

5. Trigonometric Ratios | CBSE 10th Extra Practice Question #05 | Easy Question ** Question 5** ▶

6. Trigonometry & Quadratic Equation | CBSE 10th Extra Practice Question #06 | Medium Question ** Question 6** ▶

7. Trigonometric values| CBSE 10th Extra Practice Question #07 | Easy Question ** Question 7** ▶

8. Trigonometric Ratios | CBSE 10th Extra Practice Question #08 | Easy Question ** Question 8** ▶

9. Trigonometric values | CBSE 10th Extra Practice Question #09 | Easy Question ** Question 9** ▶

10. Trigonometric values | CBSE 10th Extra Practice Question #10 | Easy Question ** Question 10** ▶

11. Square of Trigonometric Ratios | CBSE Class 10 Extra Question #11 | Easy Question ** Question 11** ▶

12. Trigonometric values | CBSE 10th Extra Practice Question #12 | Easy questions ** Question 12** ▶

13. Trigonometric Values of Basic Angles | CBSE 10th Extra Question #13 | Easy question ** Question 13** ▶

14. Trigonometric Ratios of Specific Values | CBSE Class 10 Important Question #14 | Hard Question ** Question 14** ▶

15. Trigonometric Ratio & Linear Equations | CBSE Class 10 Important Question #15 | Hard Question ** Question 15** ▶

Copyrights © 2016 - 21 All Rights Reserved by Maxtute.com - An Ascent Education Initiative.

Privacy Policy | Terms & Conditions

**Mobile:** (91) 93822 48484

**WhatsApp:** WhatsApp Now

**Email:** learn@maxtute.com