Trigonometry (Railway Maths) (Part – III)

Total Questions: 50

41. The value of tan5°tan25°tan45°tan65°tan85° is equal to: [RRB NTPC 20/01/2021 (Evening)]

Correct Answer: (a) 1
Solution:

= tan5° · tan25° · tan45° · tan65° · tan85°
= (tan5° tan85°)(tan25° tan65°) tan45°
= 1 × 1 × 1 = 1

42. What is the value of sin(48° + θ) − cos(42° − θ) ? [RRB NTPC 21/01/2021 (Morning)]

Correct Answer: (d) 0
Solution:

sin(48° + θ) − cos(42° − θ)
= sin(48° + θ) − sin(48° + θ) = 0

43. What is the value of the following expression ? [RRB NTPC 21/01/2021 (Morning)]

(tan2° · tan88°)(tan3° · tan87°) … (tan43° · tan47°) tan45°

Correct Answer: (c) 1
Solution:

tanθ tan(90° − θ) = tanθ × cotθ = 1
(tan2° tan88°)(tan3° tan87°) … (tan43° tan47°) tan45°
= 1 × tan45° = 1

44. Answer the following question? [RRB NTPC 21/01/2021 (Evening) ]

Correct Answer: (c) 300°
Solution:

45. The expression tanA / 1 - cot A + cot A / 1 - tan A can be written as: [RRB NTPC 21/01/2021 (Evening) ]

Correct Answer: (c) 1 + secAcosecA
Solution:

46. If the ratio of the sine of an acute angle to its cosine is 5 : 12, then what will the value of sine of that angle be ? [RRB NTPC 22/01/2021 (Morning) ]

Correct Answer: (a) 5/13
Solution:

47. If x = acosecθ + bcotθ, y = bcosecθ + acotθ, then what will be the value of x² - y²? [RRB NTPC 22/01/2021 (Evening) ]

Correct Answer: (a) a² - b²
Solution:

48. What is the value of 1 - tan²A / 1 + tan²A? [RRB NTPC 22/01/2021 (Evening) ]

Correct Answer: (a) cos2A
Solution:

49. Answer the following question? [RRB NTPC 22/01/2021 (Evening) ]

Correct Answer: (b) 60°
Solution:

50. The value of [RRB NTPC 22/01/2021 (Evening) ]

Correct Answer: (a) -5/2
Solution: