Trigonometry ( 11 to 15 )

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Trigonometry ( 11 to 15 ):


APTITUDE QUESTIONS (TRIGONOMETRY):

11. If sin θ = 2ab / a2+b2 , then the value of tan is equal to

A)    a2b2   / 2ab

B)    2ab / a2-b

C)    a2b / a2+b

D)    a2+b / a2-b

E)    None of these

View Answer

Answer: option  (B)

Explanation:

 

12. How many degrees are there in an angle which equals two-third of its complement?

A)    36º

B)    45º

C)    48º

D)    60º

E)    None of these

View Answer

Answer: option  (A)

Explanation:
Given, α + β = 90 …(i)
By given condition,
β = (2/3) α
∴ β = 2/3 (90ºβ) [from eq. i] => β = 60º β => (2/3) β = 36º


 

13. If sin B = 1/2 , then 3 cos B – 4 cos3 B is equal to

A)    1

B)    3/4

C)    0

D)    2 (1/2)

E)    None of these

View Answer

Answer: option  (C)

Explanation:

 

14. If sec α = 5/4 , then tan α / 1+tanα is equal to

A)    sin α/sec α

B)    sin α cos α

C)    cos 2α

D)    tan α

E)    None of these

View Answer

Answer: option  (B)

Explanation:
tan α / 1+tan2 α = cos α / sec2 α
=sin α / cos α  * (cos2 α  / 1)= sin α . cos α

 

15. What is the value of cos 1º cos 2º cos 3º ….cos 90º?

A)    1/2

B)    0

C)    1

D)    2

E)    None of these

View Answer

Answer: option  (B)

Explanation:
∵ cos 90º = 0
∴ cos 1º cos 2º cos 3º ….cos 90º = 0

 

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