Trigonometry (Railway Maths) (Part – VI)

Total Questions: 31

1. If tan 2A = cot(A - 18°) and 2A is an acute angle, then find 'A'. [RRB JE 22/05/2019 (Evening) ]

Correct Answer: (a) 36°
Solution:

tan 2A = cot(A - 18°)
tan 2A = tan (90 - A + 18)
2A = 108 - A ⇒ 3A = 108 ⇒ A = 36°

2. Simplify: [RRB JE 23/05/2019 (Evening) ]

cos 18° + cos 162° + sin 126° + sin 234°

Correct Answer: (d) 0
Solution:

cos 18° + cos 162° + sin 126° + sin 234°
= cos 18° + cos (180 - 18)° + sin (180 - 54)° + sin (180 + 54)°
= cos 18° - cos 18° + sin 54° - sin 54° = 0

3. Find the value of sin 75°. [RRB JE 23/05/2019 (Evening) ]

Correct Answer: (b)
Solution:

Formula :- Sin (A + B) = sinA cosB + cosA sinB
Sin 75° = sin (30 + 45)° = sin 30°cos 45°
+ cos 30° sin 45°

4. Find the value of sin(180° - θ) cos(90° - θ) - cos(180° - θ) sin(90° - θ). [RRB JE 24/05/2019 (Evening)]

Correct Answer: (b) 1
Solution:

5. Simplify: cos 5° + cos 24° + cos 175° + cos 204° + cos 300°. [RRB JE 25/05/2019 (Morning)]

Correct Answer: (c) 1/2
Solution:

6. In a right triangle, the sides are in the ratio 1 : 1 : √2. [RRB JE 25/05/2019 (Morning) ]

Find cos A cos B - sin A sin B

Correct Answer: (a) 0
Solution:

7. Find the value of cos(A + B), if tan A = 3/4 and tan B = 5/12 and A and B are in quadrant I. [RRB JE 25/05/2019 (Afternoon)]

Correct Answer: (a) 33/65
Solution:

8. Find the value of 'θ', where 'θ' is acute. [RRB JE 28/05/2019 (Afternoon) ]

Correct Answer: (d) 60°
Solution:

9. Find the answer of given question? [RRB JE 28/05/2019 (Afternoon) ]

Correct Answer: (d) sec A
Solution:

10. If x = a sec θ + b tan θ and y = a tan θ + b sec θ, then find x² - y². [RRB JE 29/05/2019 (Evening)]

Correct Answer: (d) a² - b²
Solution: