Trigonometry (Railway Maths) (Part – I)

Total Questions: 50

31. In any triangle ABC, a + b + c = 2s with usual notation, then sin(A/2) =? [NTPC CBT - I 07/01/2021 (Evening) ]

Correct Answer: (b)
Solution:

32. Value of A for the equation: [NTPC CBT - I 07/01/2021 (Evening) ]

tanA + tan2A + tan3A = tanA tan2A tan3A  is:

Correct Answer: (b) π/3, 2π/3
Solution:

33. If A , B and C are the interior angles of a Δ ABC , simplify [NTPC CBT - I 10/01/2021 (Morning) ]

Correct Answer: (a) 1
Solution:

34. If x = rsinAcosC , y = rsinAsinC, and z = rcosA, then find the value of x² + y² + z². [NTPC CBT - I 11/01/2021 (Morning) ]

Correct Answer: (a) r²
Solution:

35. If sin(A + B) = √3/2 and cos(A - B) = √3/2, then which of the following will be possible values of A and B? [NTPC CBT - I 12/01/2021 (Morning) ]

Correct Answer: (d) A = 45°, B = 15°
Solution:

36. If sin(3x - 20)° = cos(20 - 3y)°, then value of x - y will be: [NTPC CBT - I 12/01/2021 (Evening) ]

Correct Answer: (c) 30°
Solution:

sin(3x - 20)° = cos (20 - 3y)°
⇒ cos(90° - (3x - 20°)) = cos (20 - 3y)°
⇒ 110° - 3x = 20° - 3y
⇒ 90° = 3x - 3y
⇒ 3 (x - y) = 90° ⇒ x - y = 30°

37. If acosθ - bsinθ = c, then find the value of asinθ + bcosθ. [NTPC CBT - I 16/01/2021 (Morning) ]

Correct Answer: (b)
Solution:

38. What is the value of the following expressions? 1 + secθ + tanθ / 1 + secθ - tanθ [NTPC CBT - I 18/01/2021 (Evening) ]

Correct Answer: (c)
Solution:

39. The value of 4 cos(π/6 − α) sin(π/3 − α) is equal to: [NTPC CBT-I 18/01/2021 (Evening)]

Correct Answer: (d) 3 − 4 sin²α
Solution:

40. If tanθ = x − 1/(4x), then secθ − tanθ is equal to: [NTPC CBT-I 19/01/2021 (Morning)]

Correct Answer: (d) −2x or 1/(2x)
Solution: