RD Sharma Solutions Class 10 Maths Chapter 6 Exercise 6.1: Chapter 6 of RD Sharma’s Class 10 Maths book covers Trigonometric Identities and provides foundational knowledge on trigonometric functions and their identities.
These identities are essential for simplifying complex trigonometric expressions and solving equations. The exercise includes questions that require students to apply these identities to verify equalities or transform expressions, enhancing problem-solving skills in trigonometry. This section forms the basis for more advanced trigonometric concepts in later chapters.RD Sharma Solutions Class 10 Maths Chapter 6 Exercise 6.1 PDF
Prove the following trigonometric identities:
1. (1 – cos 2 A) cosec 2 A = 1
Solution:
Taking the L.H.S, (1 – cos 2 A) cosec 2 A = (sin 2 A) cosec 2 A [∵ sin 2 A + cos 2 A = 1 ⇒1 – sin 2 A = cos 2 A] = 1 2 = 1 = R.H.S – Hence Proved2. (1 + cot 2 A) sin 2 A = 1
Solution:
By using the identity, cosec 2 A – cot 2 A = 1 ⇒ cosec 2 A = cot 2 A + 1 Taking, L.H.S = (1 + cot 2 A) sin 2 A = cosec 2 A sin 2 A = (cosec A sin A) 2 = ((1/sin A) × sin A) 2 = (1) 2 = 1 = R.H.S – Hence Proved3. tan 2 θ cos 2 θ = 1 − cos 2 θ
Solution:
We know that, sin 2 θ + cos 2 θ = 1 Taking, L.H.S = tan 2 θ cos 2 θ = (tan θ × cos θ) 2 = (sin θ) 2 = sin 2 θ = 1 – cos 2 θ = R.H.S – Hence Proved4. cosec θ √(1 – cos 2 θ) = 1
Solution:
Using identity, sin 2 θ + cos 2 θ = 1 ⇒ sin 2 θ = 1 – cos 2 θ Taking L.H.S, L.H.S = cosec θ √(1 – cos 2 θ) = cosec θ √( sin 2 θ) = cosec θ x sin θ = 1 = R.H.S – Hence Proved5. (sec 2 θ − 1)(cosec 2 θ − 1) = 1
Solution:
Using identities, (sec 2 θ − tan 2 θ) = 1 and (cosec 2 θ − cot 2 θ) = 1 We have, L.H.S = (sec 2 θ – 1)(cosec 2 θ – 1) = tan 2 θ × cot 2 θ = (tan θ × cot θ) 2 = (tan θ × 1/tan θ) 2 = 1 2 = 1 = R.H.S – Hence Proved6. tan θ + 1/ tan θ = sec θ cosec θ
Solution:
We have, L.H.S = tan θ + 1/ tan θ = (tan 2 θ + 1)/ tan θ = sec 2 θ / tan θ [∵ sec 2 θ − tan 2 θ = 1] = (1/cos 2 θ) x 1/ (sin θ/cos θ) [∵ tan θ = sin θ / cos θ] = cos θ/ (sin θ x cos 2 θ) = 1/ cos θ x 1/ sin θ = sec θ x cosec θ = sec θ cosec θ = R.H.S – Hence Proved7. cos θ/ (1 – sin θ) = (1 + sin θ)/ cos θ
Solution:
We know that, sin 2 θ + cos 2 θ = 1 So, by multiplying both the numerator and the denominator by (1+ sin θ), we getSolution:
We know that, sin 2 θ + cos 2 θ = 1 So, by multiplying both the numerator and the denominator by (1- sin θ), we get9. cos 2 θ + 1/(1 + cot 2 θ) = 1
Solution:
We already know that, cosec 2 θ − cot 2 θ = 1 and sin 2 θ + cos 2 θ = 1 Taking L.H.S,
10. sin 2 A + 1/(1 + tan 2 A) = 1
Solution:
We already know that, sec 2 θ − tan 2 θ = 1 and sin 2 θ + cos 2 θ = 1 Taking L.H.S,11.
Solution:
We know that, sin 2 θ + cos 2 θ = 1 Taking the L.H.S,12. 1 – cos θ/ sin θ = sin θ/ 1 + cos θ
Solution:
We know that, sin 2 θ + cos 2 θ = 1 So, by multiplying both the numerator and the denominator by (1+ cos θ), we get13. sin θ/ (1 – cos θ) = cosec θ + cot θ
Solution:
Taking L.H.S,14. (1 – sin θ) / (1 + sin θ) = (sec θ – tan θ) 2
Solution:
Taking the L.H.S,
15.
Solution:
Taking L.H.S,16. tan 2 θ − sin 2 θ = tan 2 θ sin 2 θ
Solution:
Taking L.H.S, L.H.S = tan 2 θ − sin 2 θ17. (cosec θ + sin θ)(cosec θ – sin θ) = cot 2 θ + cos 2 θ
Solution:
Taking L.H.S = (cosec θ + sin θ)(cosec θ – sin θ) On multiplying, we get, = cosec 2 θ – sin 2 θ = (1 + cot 2 θ) – (1 – cos 2 θ) [Using cosec 2 θ − cot 2 θ = 1 and sin 2 θ + cos 2 θ = 1] = 1 + cot 2 θ – 1 + cos 2 θ = cot 2 θ + cos 2 θ = R.H.S – Hence Proved18. (sec θ + cos θ) (sec θ – cos θ) = tan 2 θ + sin 2 θ
Solution:
Taking L.H.S = (sec θ + cos θ)(sec θ – cos θ) On multiplying, we get, = sec 2 θ – sin 2 θ = (1 + tan 2 θ) – (1 – sin 2 θ) [Using sec 2 θ − tan 2 θ = 1 and sin 2 θ + cos 2 θ = 1] = 1 + tan 2 θ – 1 + sin 2 θ = tan 2 θ + sin 2 θ = R.H.S – Hence Proved19. sec A(1- sin A) (sec A + tan A) = 1
Solution:
Taking L.H.S = sec A(1 – sin A)(sec A + tan A) Substituting sec A = 1/cos A and tan A =sin A/cos A in the above, we have, L.H.S = 1/cos A (1 – sin A)(1/cos A + sin A/cos A) = 1 – sin 2 A / cos 2 A [After taking L.C.M] = cos 2 A / cos 2 A [∵ 1 – sin 2 A = cos 2 A] = 1 = R.H.S – Hence Proved20. (cosec A – sin A)(sec A – cos A)(tan A + cot A) = 1
Solution:
Taking L.H.S = (cosec A – sin A)(sec A – cos A)(tan A + cot A)
21. (1 + tan 2 θ)(1 – sin θ)(1 + sin θ) = 1
Solution:
Taking L.H.S = (1 + tan 2 θ)(1 – sin θ)(1 + sin θ) And, we know sin 2 θ + cos 2 θ = 1 and sec 2 θ – tan 2 θ = 1 So, L.H.S = (1 + tan 2 θ)(1 – sin θ)(1 + sin θ) = (1 + tan 2 θ){(1 – sin θ)(1 + sin θ)} = (1 + tan 2 θ)(1 – sin 2 θ) = sec 2 θ (cos 2 θ) = (1/ cos 2 θ) x cos 2 θ = 1 = R.H.S – Hence Proved22. sin 2 A cot 2 A + cos 2 A tan 2 A = 1
Solution:
We know that, cot 2 A = cos 2 A/ sin 2 A and tan 2 A = sin 2 A/cos 2 A Substituting the above in L.H.S, we get L.H.S = sin 2 A cot 2 A + cos 2 A tan 2 A = {sin 2 A (cos 2 A/ sin 2 A)} + {cos 2 A (sin 2 A/cos 2 A)} = cos 2 A + sin 2 A = 1 [∵ sin 2 θ + cos 2 θ = 1] = R.H.S – Hence Proved23.
Solution:
(i) Taking the L.H.S and using sin 2 θ + cos 2 θ = 1, we have L.H.S = cot θ – tan θ24. (cos 2 θ/ sin θ) – cosec θ + sin θ = 0
Solution:
Taking L.H.S and using sin 2 θ + cos 2 θ = 1, we have
25.
Solution:
Taking L.H.S,
26.
Solution:
Taking the LHS and using sin 2 θ + cos 2 θ = 1, we have
27.
Solution:
Taking the LHS and using sin 2 θ + cos 2 θ = 1, we have
28.
Solution:
Taking L.H.S,29.
Solution:
Taking L.H.S and using sin 2 θ + cos 2 θ = 1, we have
30.
Solution:
Taking LHS, we have31. sec 6 θ = tan 6 θ + 3 tan 2 θ sec 2 θ + 1
Solution:
From trig. Identities we have, sec 2 θ − tan 2 θ = 1 On cubing both sides, (sec 2 θ − tan 2 θ) 3 = 1 sec 6 θ − tan 6 θ − 3sec 2 θ tan 2 θ(sec 2 θ − tan 2 θ) = 1 [Since, (a – b) 3 = a 3 – b 3 – 3ab(a – b)] sec 6 θ − tan 6 θ − 3sec 2 θ tan 2 θ = 1 ⇒ sec 6 θ = tan 6 θ + 3sec 2 θ tan 2 θ + 1 Hence, L.H.S = R.H.S32. cosec 6 θ = cot 6 θ + 3cot 2 θ cosec 2 θ + 1
Solution:
From trig. Identities we have, cosec 2 θ − cot 2 θ = 1 On cubing both sides, (cosec 2 θ − cot 2 θ) 3 = 1 cosec 6 θ − cot 6 θ − 3cosec 2 θ cot 2 θ (cosec 2 θ − cot 2 θ) = 1 [Since, (a – b) 3 = a 3 – b 3 – 3ab(a – b)] cosec 6 θ − cot 6 θ − 3cosec 2 θ cot 2 θ = 1 ⇒ cosec 6 θ = cot 6 θ + 3 cosec 2 θ cot 2 θ + 1 Hence, L.H.S = R.H.S
33.
Solution:
Taking L.H.S and using sec 2 θ − tan 2 θ = 1 ⇒ 1 + tan 2 θ = sec 2 θSolution:
Taking L.H.S and using the identity sin 2 A + cos 2 A = 1, we get sin 2 A = 1 − cos 2 A ⇒ sin 2 A = (1 – cos A)(1 + cos A)
35.
Solution:
We have,36.
Solution:
We have,
37. (i)
Solution:
Taking L.H.S and rationalizing the numerator and denominator with √(1 + sin A), we get(ii)
Solution:
Taking L.H.S and rationalizing the numerator and denominator with its respective conjugates, we get38. Prove that:
(i)
Solution:
Taking L.H.S and rationalizing the numerator and denominator with its respective conjugates, we get
(ii)
Solution:
Taking L.H.S and rationalizing the numerator and denominator with its respective conjugates, we get
(iii)
Solution:
Taking L.H.S and rationalizing the numerator and denominator with its respective conjugates, we get
(iv)
Solution:
Taking L.H.S, we have
39.
Solution:
Taking LHS = (sec A – tan A) 2 , we have40.
Solution:
Taking L.H.S and rationalizing the numerator and denominator with (1 – cos A), we get41.
Solution:
Considering L.H.S and taking L.C.M and simplifying, we have,42.
Solution:
Taking LHS, we have
43.
Solution:
Considering L.H.S and taking L.C.M and simplifying, we have,