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Question 17 (OR 2
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Prove that sin θ (1 + tan θ) + cos θ (1 + cot θ) = sec θ + cosec θ

Last updated at Oct. 1, 2019 by Teachoo

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Question 17 (OR 2
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Prove that sin θ (1 + tan θ) + cos θ (1 + cot θ) = sec θ + cosec θ

Transcript

Question 17 (OR 2nd question) Prove that sin θ (1 + tan θ) + cos θ (1 + cot θ) = sec θ + cosec θ Solving LHS sin θ (1 + tan θ) + cos θ (1 + cot θ) = sin θ (1 + sin𝜃/cos𝜃 ) + cos θ (1 + cos𝜃/sin𝜃 ) = sin θ ((cos𝜃 + sin𝜃)/cos𝜃 ) + cos θ ((sin𝜃 + cos𝜃)/sin𝜃 ) Taking cos𝜃 + sin𝜃 common = (cos𝜃 + sin𝜃) (sin𝜃/cos𝜃 +cos𝜃/sin𝜃 ) = (cos𝜃 + sin𝜃) ((sin𝜃 × sin𝜃 + cos𝜃 × cos𝜃)/(cos𝜃 sin𝜃 )) = (cos𝜃 + sin𝜃) ((sin^2𝜃 + cos^2𝜃 )/(cos𝜃 sin𝜃 )) Since sin^2𝜃 + cos^2𝜃 = 1 = (cos𝜃 + sin𝜃) ((1 )/(cos𝜃 sin𝜃 )) = (cos𝜃 )/(cos𝜃 sin𝜃 ) + (sin𝜃 )/(cos𝜃 sin𝜃 ) = (1 )/sin𝜃 + (1 )/cos𝜃 = cosec θ + sec θ = RHS Thus LHS = RHS Hence proved

CBSE Class 10 Sample Paper for 2019 Boards

Paper Summary

Question 1

Question 2 (Or 1st)

Question 2 (Or 2nd)

Question 3 (Or 1st)

Question 3 (Or 2nd)

Question 4

Question 5

Question 6

Question 7 (Or 1st)

Question 7 (Or 2nd)

Question 8 (Or 1st)

Question 8 (Or 2nd)

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16 (Or 1st)

Question 16 (Or 2nd)

Question 17 (Or 1st)

Question 17 (Or 2nd) You are here

Question 18

Question 19 (Or 1st)

Question 19 (Or 2nd)

Question 20

Question 21 (Or 1st)

Question 21 (Or 2nd)

Question 22

Question 23 (Or 1st)

Question 23 (Or 2nd)

Question 24

Question 25

Question 26

Question 27 (Or 1st)

Question 27 (Or 2nd)

Question 28 (Or 1st)

Question 28 (Or 2nd)

Question 29

Question 30

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.